Make encoded character options opt-in

cmd/traefik/traefik.go

@@ -87,10 +87,10 @@ Complete documentation is available at https://traefik.io`,
 func runCmd(staticConfiguration *static.Configuration) error {
 	configureLogging(staticConfiguration)
 
-	// Display warning to advertise for new behavior of rejecting encoded characters in the request path.
+	log.WithoutContext().Warn("Traefik can reject some encoded characters in the request path." +
-	// Deprecated: this has to be removed in the next minor/major version.
+		"When your backend is not fully compliant with [RFC 3986](https://datatracker.ietf.org/doc/html/rfc3986)," +
-	log.WithoutContext().Warnf("Starting with v2.11.32, Traefik now rejects some encoded characters in the request path by default. " +
+		"it is recommended to set these options to `false` to avoid split-view situation." +
-		"Refer to the documentation for more details: https://doc.traefik.io/traefik/v2.11/migration/v2/#encoded-characters-in-request-path")
+		"Refer to the documentation for more details: https://doc.traefik.io/traefik/v2.11/migration/v2/#encoded-characters-configuration-default-values")
 
 	http.DefaultTransport.(*http.Transport).Proxy = http.ProxyFromEnvironment
 

docs/content/migration/v2.md

@@ -737,3 +737,30 @@ Note: This check is not done against query parameters,
 but only against the request path as defined in [RFC3986 section-3](https://datatracker.ietf.org/doc/html/rfc3986#section-3).
 
 Please check out the entrypoint [encodedCharacters option](../routing/entrypoints.md#encoded-characters) documentation for more details.
+
+## v2.11.35
+
+### Encoded Characters Configuration Default Values
+
+Since `v2.11.35`, the options for encoded characters now have a `true` default value.
+This means that Traefik will not reject requests with a path containing a specific set of encoded characters by default.
+It is now up to the users to configure the security hardening of encoded characters.
+
+Here is the list of the encoded characters that can be configured to `false` to disallow them:
+
+| Encoded Character | Character               | Config options                                                                       | Default value |
+|-------------------|-------------------------|--------------------------------------------------------------------------------------|---------------|
+| `%2f` or `%2F`    | `/` (slash)             | `entryPoints.<name>`<br/>`.http.encodedCharacters`<br/>`.allowEncodedSlash`          | `true`        |
+| `%5c` or `%5C`    | `\` (backslash)         | `entryPoints.<name>.`<br/>`.http.encodedCharacters`<br/>`.allowEncodedBackSlash`     | `true`        |
+| `%00`             | `NULL` (null character) | `entryPoints.<name>.`<br/>`.http.encodedCharacters`<br/>`.allowEncodedNullCharacter` | `true`        |
+| `%3b` or `%3B`    | `;` (semicolon)         | `entryPoints.<name>.`<br/>`.http.encodedCharacters`<br/>`.allowEncodedSemicolon`     | `true`        |
+| `%25`             | `%` (percent)           | `entryPoints.<name>.`<br/>`.http.encodedCharacters`<br/>`.allowEncodedPercent`       | `true`        |
+| `%3f` or `%3F`    | `?` (question mark)     | `entryPoints.<name>.`<br/>`.http.encodedCharacters`<br/>`.allowEncodedQuestionMark`  | `true`        |
+| `%23`             | `#` (hash)              | `entryPoints.<name>.`<br/>`.http.encodedCharacters`<br/>`.allowEncodedHash`          | `true`        |
+
+Note: This check is not done against query parameters,
+but only against the request path as defined
+in [RFC3986 section-3](https://datatracker.ietf.org/doc/html/rfc3986#section-3).
+
+Please check out the entrypoint [encodedCharacters option](../routing/entrypoints.md#encoded-characters) documentation
+for more details.

docs/content/reference/static-configuration/cli-ref.md

@@ -124,25 +124,25 @@ Trust only forwarded headers from selected IPs.
 HTTP configuration.
 
 `--entrypoints.<name>.http.encodedcharacters.allowencodedbackslash`:  
-Defines whether requests with encoded back slash characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded back slash characters in the path are allowed. (Default: ```true```)
 
 `--entrypoints.<name>.http.encodedcharacters.allowencodedhash`:  
-Defines whether requests with encoded hash characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded hash characters in the path are allowed. (Default: ```true```)
 
 `--entrypoints.<name>.http.encodedcharacters.allowencodednullcharacter`:  
-Defines whether requests with encoded null characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded null characters in the path are allowed. (Default: ```true```)
 
 `--entrypoints.<name>.http.encodedcharacters.allowencodedpercent`:  
-Defines whether requests with encoded percent characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded percent characters in the path are allowed. (Default: ```true```)
 
 `--entrypoints.<name>.http.encodedcharacters.allowencodedquestionmark`:  
-Defines whether requests with encoded question mark characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded question mark characters in the path are allowed. (Default: ```true```)
 
 `--entrypoints.<name>.http.encodedcharacters.allowencodedsemicolon`:  
-Defines whether requests with encoded semicolon characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded semicolon characters in the path are allowed. (Default: ```true```)
 
 `--entrypoints.<name>.http.encodedcharacters.allowencodedslash`:  
-Defines whether requests with encoded slash characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded slash characters in the path are allowed. (Default: ```true```)
 
 `--entrypoints.<name>.http.encodequerysemicolons`:  
 Defines whether request query semicolons should be URLEncoded. (Default: ```false```)

docs/content/reference/static-configuration/env-ref.md

@@ -133,25 +133,25 @@ HTTP/3 configuration. (Default: ```false```)
 UDP port to advertise, on which HTTP/3 is available. (Default: ```0```)
 
 `TRAEFIK_ENTRYPOINTS_<NAME>_HTTP_ENCODEDCHARACTERS_ALLOWENCODEDBACKSLASH`:  
-Defines whether requests with encoded back slash characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded back slash characters in the path are allowed. (Default: ```true```)
 
 `TRAEFIK_ENTRYPOINTS_<NAME>_HTTP_ENCODEDCHARACTERS_ALLOWENCODEDHASH`:  
-Defines whether requests with encoded hash characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded hash characters in the path are allowed. (Default: ```true```)
 
 `TRAEFIK_ENTRYPOINTS_<NAME>_HTTP_ENCODEDCHARACTERS_ALLOWENCODEDNULLCHARACTER`:  
-Defines whether requests with encoded null characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded null characters in the path are allowed. (Default: ```true```)
 
 `TRAEFIK_ENTRYPOINTS_<NAME>_HTTP_ENCODEDCHARACTERS_ALLOWENCODEDPERCENT`:  
-Defines whether requests with encoded percent characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded percent characters in the path are allowed. (Default: ```true```)
 
 `TRAEFIK_ENTRYPOINTS_<NAME>_HTTP_ENCODEDCHARACTERS_ALLOWENCODEDQUESTIONMARK`:  
-Defines whether requests with encoded question mark characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded question mark characters in the path are allowed. (Default: ```true```)
 
 `TRAEFIK_ENTRYPOINTS_<NAME>_HTTP_ENCODEDCHARACTERS_ALLOWENCODEDSEMICOLON`:  
-Defines whether requests with encoded semicolon characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded semicolon characters in the path are allowed. (Default: ```true```)
 
 `TRAEFIK_ENTRYPOINTS_<NAME>_HTTP_ENCODEDCHARACTERS_ALLOWENCODEDSLASH`:  
-Defines whether requests with encoded slash characters in the path are allowed. (Default: ```false```)
+Defines whether requests with encoded slash characters in the path are allowed. (Default: ```true```)
 
 `TRAEFIK_ENTRYPOINTS_<NAME>_HTTP_ENCODEQUERYSEMICOLONS`:  
 Defines whether request query semicolons should be URLEncoded. (Default: ```false```)

docs/content/routing/entrypoints.md

@@ -129,13 +129,13 @@ They can be defined by using a file (YAML or TOML) or CLI arguments.
             - "192.168.0.1"
         http:
           encodedCharacters:
-            allowEncodedSlash: true
+            allowEncodedSlash: false
-            allowEncodedBackSlash: true
+            allowEncodedBackSlash: false
-            allowEncodedNullCharacter: true
+            allowEncodedNullCharacter: false
-            allowEncodedSemicolon: true
+            allowEncodedSemicolon: false
-            allowEncodedPercent: true
+            allowEncodedPercent: false
-            allowEncodedQuestionMark: true
+            allowEncodedQuestionMark: false
-            allowEncodedHash: true
+            allowEncodedHash: false
     ```
 
     ```toml tab="File (TOML)"
@@ -162,13 +162,13 @@ They can be defined by using a file (YAML or TOML) or CLI arguments.
           insecure = true
           trustedIPs = ["127.0.0.1", "192.168.0.1"]
         [entryPoints.name.http.encodedCharacters]
-          allowEncodedSlash = true
+          allowEncodedSlash = false
-          allowEncodedBackSlash = true
+          allowEncodedBackSlash = false
-          allowEncodedNullCharacter = true
+          allowEncodedNullCharacter = false
-          allowEncodedSemicolon = true
+          allowEncodedSemicolon = false
-          allowEncodedPercent = true
+          allowEncodedPercent = false
-          allowEncodedQuestionMark = true
+          allowEncodedQuestionMark = false
-          allowEncodedHash = true
+          allowEncodedHash = false
     ```
 
     ```bash tab="CLI"
@@ -185,13 +185,13 @@ They can be defined by using a file (YAML or TOML) or CLI arguments.
     --entryPoints.name.proxyProtocol.trustedIPs=127.0.0.1,192.168.0.1
     --entryPoints.name.forwardedHeaders.insecure=true
     --entryPoints.name.forwardedHeaders.trustedIPs=127.0.0.1,192.168.0.1
-    --entryPoints.name.http.encodedCharacters.allowEncodedSlash=true
+    --entryPoints.name.http.encodedCharacters.allowEncodedSlash=false
-    --entryPoints.name.http.encodedCharacters.allowEncodedBackSlash=true
+    --entryPoints.name.http.encodedCharacters.allowEncodedBackSlash=false
-    --entryPoints.name.http.encodedCharacters.allowEncodedNullCharacter=true
+    --entryPoints.name.http.encodedCharacters.allowEncodedNullCharacter=false
-    --entryPoints.name.http.encodedCharacters.allowEncodedSemicolon=true
+    --entryPoints.name.http.encodedCharacters.allowEncodedSemicolon=false
-    --entryPoints.name.http.encodedCharacters.allowEncodedPercent=true
+    --entryPoints.name.http.encodedCharacters.allowEncodedPercent=false
-    --entryPoints.name.http.encodedCharacters.allowEncodedQuestionMark=true
+    --entryPoints.name.http.encodedCharacters.allowEncodedQuestionMark=false
-    --entryPoints.name.http.encodedCharacters.allowEncodedHash=true
+    --entryPoints.name.http.encodedCharacters.allowEncodedHash=false
     ```
 
 ### Address
@@ -1021,20 +1021,21 @@ entryPoints:
 ### Encoded Characters
 
 You can configure Traefik to control the handling of encoded characters in request paths for security purposes.
-By default, Traefik rejects requests with path containing certain encoded characters that could be used in path traversal or other security attacks.
+By default, Traefik do not reject requests with path containing certain encoded characters that could be used in path traversal or other security attacks.
 
 !!! info 
     
     This check is not done against the request query parameters,
     but only against the request path as defined in [RFC3986 section-3](https://datatracker.ietf.org/doc/html/rfc3986#section-3).
 
-!!! warning "Security Considerations"
+!!! info "Security Considerations"
 
-    Allowing certain encoded characters may expose your application to security vulnerabilities.
+    When your backend is not fully compliant with [RFC 3986](https://datatracker.ietf.org/doc/html/rfc3986) and notably decode encoded reserved characters in the requets path,
+    it is recommended to set these options to `false` to avoid split-view situation and helps prevent path traversal attacks or other malicious attempts to bypass security controls.
 
 ??? info "`encodedCharacters.allowEncodedSlash`"
 
-    _Optional, Default=false_
+    _Optional, Default=true_
 
     Controls whether requests with encoded slash characters (`%2F` or `%2f`) in the path are allowed.
 
@@ -1045,7 +1046,7 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address: ":80"
         http:
           encodedCharacters:
-            allowEncodedSlash: true
+            allowEncodedSlash: false
     ```
 
     ```toml tab="File (TOML)"
@@ -1055,18 +1056,18 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address = ":80"
 
         [entryPoints.web.http.encodedCharacters]
-          allowEncodedSlash = true
+          allowEncodedSlash = false
     ```
 
     ```bash tab="CLI"
     ## Static configuration
     --entryPoints.web.address=:80
-    --entryPoints.web.http.encodedCharacters.allowEncodedSlash=true
+    --entryPoints.web.http.encodedCharacters.allowEncodedSlash=false
     ```
 
 ??? info "`encodedCharacters.allowEncodedBackSlash`"
 
-    _Optional, Default=false_
+    _Optional, Default=true_
 
     Controls whether requests with encoded back slash characters (`%5C` or `%5c`) in the path are allowed.
 
@@ -1077,7 +1078,7 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address: ":80"
         http:
           encodedCharacters:
-            allowEncodedBackSlash: true
+            allowEncodedBackSlash: false
     ```
 
     ```toml tab="File (TOML)"
@@ -1087,18 +1088,18 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address = ":80"
 
         [entryPoints.web.http.encodedCharacters]
-          allowEncodedBackSlash = true
+          allowEncodedBackSlash = false
     ```
 
     ```bash tab="CLI"
     ## Static configuration
     --entryPoints.web.address=:80
-    --entryPoints.web.http.encodedCharacters.allowEncodedBackSlash=true
+    --entryPoints.web.http.encodedCharacters.allowEncodedBackSlash=false
     ```
 
 ??? info "`encodedCharacters.allowEncodedNullCharacter`"
 
-    _Optional, Default=false_
+    _Optional, Default=true_
 
     Controls whether requests with encoded null characters (`%00`) in the path are allowed.
 
@@ -1109,7 +1110,7 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address: ":80"
         http:
           encodedCharacters:
-            allowEncodedNullCharacter: true
+            allowEncodedNullCharacter: false
     ```
 
     ```toml tab="File (TOML)"
@@ -1119,18 +1120,18 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address = ":80"
 
         [entryPoints.web.http.encodedCharacters]
-          allowEncodedNullCharacter = true
+          allowEncodedNullCharacter = false
     ```
 
     ```bash tab="CLI"
     ## Static configuration
     --entryPoints.web.address=:80
-    --entryPoints.web.http.encodedCharacters.allowEncodedNullCharacter=true
+    --entryPoints.web.http.encodedCharacters.allowEncodedNullCharacter=false
     ```
 
 ??? info "`encodedCharacters.allowEncodedSemicolon`"
 
-    _Optional, Default=false_
+    _Optional, Default=true_
 
     Controls whether requests with encoded semicolon characters (`%3B` or `%3b`) in the path are allowed.
 
@@ -1141,7 +1142,7 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address: ":80"
         http:
           encodedCharacters:
-            allowEncodedSemicolon: true
+            allowEncodedSemicolon: false
     ```
 
     ```toml tab="File (TOML)"
@@ -1151,18 +1152,18 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address = ":80"
 
         [entryPoints.web.http.encodedCharacters]
-          allowEncodedSemicolon = true
+          allowEncodedSemicolon = false
     ```
 
     ```bash tab="CLI"
     ## Static configuration
     --entryPoints.web.address=:80
-    --entryPoints.web.http.encodedCharacters.allowEncodedSemicolon=true
+    --entryPoints.web.http.encodedCharacters.allowEncodedSemicolon=false
     ```
 
 ??? info "`encodedCharacters.allowEncodedPercent`"
 
-    _Optional, Default=false_
+    _Optional, Default=true_
 
     Controls whether requests with encoded percent characters (`%25`) in the path are allowed.
 
@@ -1173,7 +1174,7 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address: ":80"
         http:
           encodedCharacters:
-            allowEncodedPercent: true   
+            allowEncodedPercent: false   
     ```
 
     ```toml tab="File (TOML)"
@@ -1183,18 +1184,18 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address = ":80"
 
         [entryPoints.web.http.encodedCharacters]
-          allowEncodedPercent = true
+          allowEncodedPercent = false
     ```
 
     ```bash tab="CLI"
     ## Static configuration
     --entryPoints.web.address=:80
-    --entryPoints.web.http.encodedCharacters.allowEncodedPercent=true
+    --entryPoints.web.http.encodedCharacters.allowEncodedPercent=false
     ```
 
 ??? info "`encodedCharacters.allowEncodedQuestionMark`"
 
-    _Optional, Default=false_
+    _Optional, Default=true_
 
     Controls whether requests with encoded question mark characters (`%3F` or `%3f`) in the path are allowed.
 
@@ -1205,7 +1206,7 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address: ":80"
         http:
           encodedCharacters:
-            allowEncodedQuestionMark: true
+            allowEncodedQuestionMark: false
     ```
 
     ```toml tab="File (TOML)"
@@ -1215,18 +1216,18 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address = ":80"
 
         [entryPoints.web.http.encodedCharacters]
-          allowEncodedQuestionMark = true
+          allowEncodedQuestionMark = false
     ```
 
     ```bash tab="CLI"
     ## Static configuration
     --entryPoints.web.address=:80
-    --entryPoints.web.http.encodedCharacters.allowEncodedQuestionMark=true
+    --entryPoints.web.http.encodedCharacters.allowEncodedQuestionMark=false
     ```
 
 ??? info "`encodedCharacters.allowEncodedHash`"
 
-    _Optional, Default=false_
+    _Optional, Default=true_
 
     Controls whether requests with encoded hash characters (`%23`) in the path are allowed.
 
@@ -1237,7 +1238,7 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address: ":80"
         http:    
           encodedCharacters:
-            allowEncodedHash: true
+            allowEncodedHash: false
     ```
 
     ```toml tab="File (TOML)"
@@ -1247,13 +1248,13 @@ By default, Traefik rejects requests with path containing certain encoded charac
         address = ":80"
 
         [entryPoints.web.http.encodedCharacters]
-          allowEncodedHash = true
+          allowEncodedHash = false
     ```
 
     ```bash tab="CLI"
     ## Static configuration
     --entryPoints.web.address=:80
-    --entryPoints.web.http.encodedCharacters.allowEncodedHash=true
+    --entryPoints.web.http.encodedCharacters.allowEncodedHash=false
     ```
 
 ### SanitizePath

docs/content/security/request-path.md

@@ -20,7 +20,7 @@ When Traefik receives an HTTP request, it processes the request path through sev
 
 Traefik inspects the path for potentially dangerous encoded characters and rejects requests containing them unless explicitly allowed.
 
-Here is the list of the encoded characters that are rejected by default:
+Here is the list of the encoded characters that are allowed by default:
 
 | Encoded Character | Character               |
 |-------------------|-------------------------|
@@ -87,7 +87,12 @@ Configure it in the [EntryPoints](../routing/entrypoints.md#encoded-characters)
 
 This filtering occurs before path sanitization and catches attack attempts that use encoding to bypass other security controls.
 
-All encoded character filtering is enabled by default (`false` means encoded characters are rejected), providing maximum security:
+All encoded character filtering is disabled by default (`true` means encoded characters are allowed).
+
+!!! info "Security Considerations"
+
+    When your backend is not fully compliant with [RFC 3986](https://datatracker.ietf.org/doc/html/rfc3986) and notably decode encoded reserved characters in the requets path,
+    it is recommended to set these options to `false` to avoid split-view situation and helps prevent path traversal attacks or other malicious attempts to bypass security controls.
 
 ```yaml tab="File (YAML)"
 entryPoints:
@@ -95,13 +100,13 @@ entryPoints:
     address: ":443"
     http:
       encodedCharacters:
-        allowEncodedSlash: false          # %2F - Default: false (RECOMMENDED)
+        allowEncodedSlash: false          # %2F - Default: true
-        allowEncodedBackSlash: false      # %5C - Default: false (RECOMMENDED)
+        allowEncodedBackSlash: false      # %5C - Default: true
-        allowEncodedNullCharacter: false  # %00 - Default: false (RECOMMENDED)
+        allowEncodedNullCharacter: false  # %00 - Default: true
-        allowEncodedSemicolon: false      # %3B - Default: false (RECOMMENDED)
+        allowEncodedSemicolon: false      # %3B - Default: true
-        allowEncodedPercent: false        # %25 - Default: false (RECOMMENDED)
+        allowEncodedPercent: false        # %25 - Default: true
-        allowEncodedQuestionMark: false   # %3F - Default: false (RECOMMENDED)
+        allowEncodedQuestionMark: false   # %3F - Default: true
-        allowEncodedHash: false           # %23 - Default: false (RECOMMENDED)
+        allowEncodedHash: false           # %23 - Default: true
 ```
 
 ```toml tab="File (TOML)"

integration/fixtures/simple_encoded_chars.toml

@@ -8,12 +8,18 @@
 [entryPoints]
   [entryPoints.strict]
     address = ":8000"
-    # Default: no encoded characters allowed
+    [entryPoints.strict.http.encodedCharacters]
+        allowEncodedSlash = false
 
   [entryPoints.permissive]
     address = ":8001"
+    # No config, default values should apply
+
+  [entryPoints.permissive2]
+    address = ":8002"
+    # No config for allowEncodedSlash, default value is effectively true
     [entryPoints.permissive.http.encodedCharacters]
-      allowEncodedSlash = true
+        allowEncodedBackSlash = false
 
 [api]
   insecure = true

integration/fixtures/websocket/config.toml

@@ -8,8 +8,6 @@
 [entryPoints]
   [entryPoints.web]
     address = ":8000"
-    [entryPoints.web.http.encodedCharacters]
-        allowEncodedSlash = true
 
 [api]
   insecure = true

integration/simple_test.go

@@ -1520,6 +1520,12 @@ func (s *SimpleSuite) TestEncodedCharactersDifferentEntryPoints() {
 			target:   "127.0.0.1:8001", // permissive entry point
 			expected: http.StatusOK,
 		},
+		{
+			desc:     "Encoded slash should be ALLOWED on permissive2 entry point",
+			request:  "GET /path%2Fwith%2Fslash HTTP/1.1\r\nHost: test.localhost\r\n\r\n",
+			target:   "127.0.0.1:8002", // permissive2 entry point
+			expected: http.StatusOK,
+		},
 		{
 			desc:     "Regular path should work on strict entry point",
 			request:  "GET /regular/path HTTP/1.1\r\nHost: test.localhost\r\n\r\n",
@@ -1532,6 +1538,12 @@ func (s *SimpleSuite) TestEncodedCharactersDifferentEntryPoints() {
 			target:   "127.0.0.1:8001",
 			expected: http.StatusOK,
 		},
+		{
+			desc:     "Regular path should work on permissive2 entry point",
+			request:  "GET /regular/path HTTP/1.1\r\nHost: test.localhost\r\n\r\n",
+			target:   "127.0.0.1:8002",
+			expected: http.StatusOK,
+		},
 	}
 
 	for _, test := range testCases {

pkg/config/dynamic/http_config.go

@@ -43,14 +43,14 @@ type Service struct {
 
 // Router holds the router configuration.
 type Router struct {
-	EntryPoints                 []string                          `json:"entryPoints,omitempty" toml:"entryPoints,omitempty" yaml:"entryPoints,omitempty" export:"true"`
+	EntryPoints                 []string                           `json:"entryPoints,omitempty" toml:"entryPoints,omitempty" yaml:"entryPoints,omitempty" export:"true"`
-	Middlewares                 []string                          `json:"middlewares,omitempty" toml:"middlewares,omitempty" yaml:"middlewares,omitempty" export:"true"`
+	Middlewares                 []string                           `json:"middlewares,omitempty" toml:"middlewares,omitempty" yaml:"middlewares,omitempty" export:"true"`
-	Service                     string                            `json:"service,omitempty" toml:"service,omitempty" yaml:"service,omitempty" export:"true"`
+	Service                     string                             `json:"service,omitempty" toml:"service,omitempty" yaml:"service,omitempty" export:"true"`
-	Rule                        string                            `json:"rule,omitempty" toml:"rule,omitempty" yaml:"rule,omitempty"`
+	Rule                        string                             `json:"rule,omitempty" toml:"rule,omitempty" yaml:"rule,omitempty"`
-	Priority                    int                               `json:"priority,omitempty" toml:"priority,omitempty,omitzero" yaml:"priority,omitempty" export:"true"`
+	Priority                    int                                `json:"priority,omitempty" toml:"priority,omitempty,omitzero" yaml:"priority,omitempty" export:"true"`
-	TLS                         *RouterTLSConfig                  `json:"tls,omitempty" toml:"tls,omitempty" yaml:"tls,omitempty" label:"allowEmpty" file:"allowEmpty" kv:"allowEmpty" export:"true"`
+	TLS                         *RouterTLSConfig                   `json:"tls,omitempty" toml:"tls,omitempty" yaml:"tls,omitempty" label:"allowEmpty" file:"allowEmpty" kv:"allowEmpty" export:"true"`
-	DefaultRule                 bool                              `json:"-" toml:"-" yaml:"-" label:"-" file:"-"`
+	DefaultRule                 bool                               `json:"-" toml:"-" yaml:"-" label:"-" file:"-"`
-	DeniedEncodedPathCharacters RouterDeniedEncodedPathCharacters `json:"-" toml:"-" yaml:"-" label:"-" file:"-"`
+	DeniedEncodedPathCharacters *RouterDeniedEncodedPathCharacters `json:"-" toml:"-" yaml:"-" label:"-" file:"-" kv:"-"`
 }
 
 // +k8s:deepcopy-gen=true

pkg/config/dynamic/zz_generated.deepcopy.go

@@ -1035,7 +1035,11 @@ func (in *Router) DeepCopyInto(out *Router) {
 		*out = new(RouterTLSConfig)
 		(*in).DeepCopyInto(*out)
 	}
-	out.DeniedEncodedPathCharacters = in.DeniedEncodedPathCharacters
+	if in.DeniedEncodedPathCharacters != nil {
+		in, out := &in.DeniedEncodedPathCharacters, &out.DeniedEncodedPathCharacters
+		*out = new(RouterDeniedEncodedPathCharacters)
+		**out = **in
+	}
 	return
 }
 

pkg/config/static/entrypoints.go

@@ -84,6 +84,16 @@ type EncodedCharacters struct {
 	AllowEncodedHash          bool `description:"Defines whether requests with encoded hash characters in the path are allowed." json:"allowEncodedHash,omitempty" toml:"allowEncodedHash,omitempty" yaml:"allowEncodedHash,omitempty" export:"true"`
 }
 
+func (ec *EncodedCharacters) SetDefaults() {
+	ec.AllowEncodedSlash = true
+	ec.AllowEncodedBackSlash = true
+	ec.AllowEncodedNullCharacter = true
+	ec.AllowEncodedSemicolon = true
+	ec.AllowEncodedPercent = true
+	ec.AllowEncodedQuestionMark = true
+	ec.AllowEncodedHash = true
+}
+
 // HTTP2Config is the HTTP2 configuration of an entry point.
 type HTTP2Config struct {
 	MaxConcurrentStreams int32 `description:"Specifies the number of concurrent streams per connection that each client is allowed to initiate." json:"maxConcurrentStreams,omitempty" toml:"maxConcurrentStreams,omitempty" yaml:"maxConcurrentStreams,omitempty" export:"true"`

pkg/server/aggregator.go

@@ -167,7 +167,7 @@ func applyModel(cfg dynamic.Configuration) dynamic.Configuration {
 				if m.DeniedEncodedPathCharacters != nil {
 					// As the denied encoded path characters option is not configurable at the router level,
 					// we can simply copy the whole structure to override the router's default config.
-					cp.DeniedEncodedPathCharacters = *m.DeniedEncodedPathCharacters
+					cp.DeniedEncodedPathCharacters = m.DeniedEncodedPathCharacters
 				}
 
 				rtName := name

pkg/server/router/deny.go

@@ -2,29 +2,10 @@ package router
 
 import (
 	"net/http"
-	"strings"
 
 	"github.com/traefik/traefik/v2/pkg/log"
 )
 
-// denyFragment rejects the request if the URL path contains a fragment (hash character).
-// When go receives an HTTP request, it assumes the absence of fragment URL.
-// However, it is still possible to send a fragment in the request.
-// In this case, Traefik will encode the '#' character, altering the request's intended meaning.
-// To avoid this behavior, the following function rejects requests that include a fragment in the URL.
-func denyFragment(h http.Handler) http.Handler {
-	return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
-		if strings.Contains(req.URL.RawPath, "#") {
-			log.WithoutContext().Debugf("Rejecting request because it contains a fragment in the URL path: %s", req.URL.RawPath)
-			rw.WriteHeader(http.StatusBadRequest)
-
-			return
-		}
-
-		h.ServeHTTP(rw, req)
-	})
-}
-
 // denyEncodedPathCharacters reject the request if the escaped path contains encoded characters in the given list.
 func denyEncodedPathCharacters(encodedCharacters map[string]struct{}, h http.Handler) http.Handler {
 	return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {

pkg/server/router/deny_test.go

@@ -8,42 +8,6 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func Test_denyFragment(t *testing.T) {
-	tests := []struct {
-		name       string
-		url        string
-		wantStatus int
-	}{
-		{
-			name:       "Rejects fragment character",
-			url:        "http://example.com/#",
-			wantStatus: http.StatusBadRequest,
-		},
-		{
-			name:       "Allows without fragment",
-			url:        "http://example.com/",
-			wantStatus: http.StatusOK,
-		},
-	}
-
-	for _, test := range tests {
-		t.Run(test.name, func(t *testing.T) {
-			t.Parallel()
-
-			handler := denyFragment(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				w.WriteHeader(http.StatusOK)
-			}))
-
-			req := httptest.NewRequest(http.MethodGet, test.url, nil)
-			res := httptest.NewRecorder()
-
-			handler.ServeHTTP(res, req)
-
-			assert.Equal(t, test.wantStatus, res.Code)
-		})
-	}
-}
-
 func Test_denyEncodedPathCharacters(t *testing.T) {
 	tests := []struct {
 		name       string

pkg/server/router/router.go

@@ -223,14 +223,11 @@ func (m *Manager) buildHTTPHandler(ctx context.Context, router *runtime.RouterIn
 		chain = chain.Append(denyrouterrecursion.WrapHandler(routerName))
 	}
 
-	// Here we are adding deny handlers for encoded path characters and fragment.
+	if router.DeniedEncodedPathCharacters != nil {
-	// Deny handler are only added for root routers, child routers are protected by their parent router deny handlers.
+		chain = chain.Append(func(next http.Handler) (http.Handler, error) {
-	chain = chain.Append(func(next http.Handler) (http.Handler, error) {
+			return denyEncodedPathCharacters(router.DeniedEncodedPathCharacters.Map(), next), nil
-		return denyFragment(next), nil
+		})
-	})
+	}
-	chain = chain.Append(func(next http.Handler) (http.Handler, error) {
-		return denyEncodedPathCharacters(router.DeniedEncodedPathCharacters.Map(), next), nil
-	})
 
 	return chain.Extend(*mHandler).Append(tHandler).Then(sHandler)
 }

pkg/server/router/router_test.go

@@ -910,13 +910,16 @@ func TestManager_BuildHandlers_Deny(t *testing.T) {
 		expectedStatusCode int
 	}{
 		{
-			desc:        "unallowed request with encoded slash",
+			desc:        "disallow request with encoded slash",
 			requestPath: "/foo%2F",
 			routers: map[string]*dynamic.Router{
 				"parent": {
 					EntryPoints: []string{"web"},
 					Rule:        "PathPrefix(`/`)",
 					Service:     "service",
+					DeniedEncodedPathCharacters: &dynamic.RouterDeniedEncodedPathCharacters{
+						AllowEncodedSlash: false,
+					},
 				},
 			},
 			services: map[string]*dynamic.Service{
@@ -936,9 +939,6 @@ func TestManager_BuildHandlers_Deny(t *testing.T) {
 					EntryPoints: []string{"web"},
 					Rule:        "PathPrefix(`/`)",
 					Service:     "service",
-					DeniedEncodedPathCharacters: dynamic.RouterDeniedEncodedPathCharacters{
-						AllowEncodedSlash: true,
-					},
 				},
 			},
 			services: map[string]*dynamic.Service{
@@ -950,25 +950,6 @@ func TestManager_BuildHandlers_Deny(t *testing.T) {
 			},
 			expectedStatusCode: http.StatusBadGateway,
 		},
-		{
-			desc:        "unallowed request with fragment",
-			requestPath: "/foo#",
-			routers: map[string]*dynamic.Router{
-				"parent": {
-					EntryPoints: []string{"web"},
-					Rule:        "PathPrefix(`/`)",
-					Service:     "service",
-				},
-			},
-			services: map[string]*dynamic.Service{
-				"service": {
-					LoadBalancer: &dynamic.ServersLoadBalancer{
-						Servers: []dynamic.Server{{URL: "http://localhost:8080"}},
-					},
-				},
-			},
-			expectedStatusCode: http.StatusBadRequest,
-		},
 	}
 
 	for _, test := range testCases {

pkg/server/server_entrypoint_tcp.go

@@ -606,6 +606,8 @@ func createHTTPServer(ctx context.Context, ln net.Listener, configuration *stati
 
 	handler = normalizePath(handler)
 
+	handler = denyFragment(handler)
+
 	serverHTTP := &http.Server{
 		Protocols:    &protocols,
 		Handler:      handler,
@@ -685,6 +687,24 @@ func (t *trackedConnection) Close() error {
 	return t.WriteCloser.Close()
 }
 
+// denyFragment rejects the request if the URL path contains a fragment (hash character).
+// When go receives an HTTP request, it assumes the absence of fragment URL.
+// However, it is still possible to send a fragment in the request.
+// In this case, Traefik will encode the '#' character, altering the request's intended meaning.
+// To avoid this behavior, the following function rejects requests that include a fragment in the URL.
+func denyFragment(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+		if strings.Contains(req.URL.RawPath, "#") {
+			log.WithoutContext().Debugf("Rejecting request because it contains a fragment in the URL path: %s", req.URL.RawPath)
+			rw.WriteHeader(http.StatusBadRequest)
+
+			return
+		}
+
+		h.ServeHTTP(rw, req)
+	})
+}
+
 // This function is inspired by http.AllowQuerySemicolons.
 func encodeQuerySemicolons(h http.Handler) http.Handler {
 	return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {

pkg/server/server_entrypoint_tcp_test.go

@@ -388,6 +388,42 @@ func TestKeepAliveH2c(t *testing.T) {
 	require.Contains(t, err.Error(), "use of closed network connection")
 }
 
+func Test_denyFragment(t *testing.T) {
+	tests := []struct {
+		name       string
+		url        string
+		wantStatus int
+	}{
+		{
+			name:       "Rejects fragment character",
+			url:        "http://example.com/#",
+			wantStatus: http.StatusBadRequest,
+		},
+		{
+			name:       "Allows without fragment",
+			url:        "http://example.com/",
+			wantStatus: http.StatusOK,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			handler := denyFragment(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.WriteHeader(http.StatusOK)
+			}))
+
+			req := httptest.NewRequest(http.MethodGet, test.url, nil)
+			res := httptest.NewRecorder()
+
+			handler.ServeHTTP(res, req)
+
+			assert.Equal(t, test.wantStatus, res.Code)
+		})
+	}
+}
+
 func TestSanitizePath(t *testing.T) {
 	tests := []struct {
 		path     string