{"id":"CVE-2025-66490","revision":null,"records":[{"revision":"1619f07336374082a9ecf8f06a5816b9","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-66490","aliases":[],"title":"Traefik doesn't Prevent Path Normalization Bypass in Router + Middleware Rules","description":"Traefik is an HTTP reverse proxy and load balancer. For versions prior to 2.11.32 and 2.11.31 through 3.6.2, requests using PathPrefix, Path or PathRegex matchers can bypass path normalization. When Traefik uses path-based routing, requests containing URL-encoded restricted characters (/, \\, Null, ;, ?, #) can bypass the middleware chain and reach unintended backends. For example, a request to http://mydomain.example.com/admin%2F could reach service-a without triggering my-security-middleware, bypassing security controls for the /admin/ path. This issue is fixed in versions 2.11.32 and 3.6.3.","state":0,"publishedAt":"2025-12-09T00:35:26.53+00:00","modifiedAt":"2025-12-09T16:03:33.572+00:00","affected":[{"ecosystem":"Vendor product","name":"traefik","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"traefik\",\n                    \"product\": \"traefik\",\n                    \"versions\": [\n                        {\n                            \"version\": \"github.com/traefik/traefik/v3  < 3.6.3\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"github.com/traefik/traefik/v2 < 2.11.32\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"github.com/traefik/traefik <= 1.7.34\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N","score":6.9,"severity":"MEDIUM"}],"references":["https://github.com/traefik/traefik/security/advisories/GHSA-gm3x-23wp-hc2c","https://github.com/traefik/traefik/releases/tag/v2.11.32","https://github.com/traefik/traefik/releases/tag/v3.6.4"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-66490","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-66490","identifiers":["CVE-2025-66490"]},"retained":false,"historicalAffected":[]},{"revision":"f9b159cfd63148b397408741e5d3047b","observedAt":"2026-11-09T04:09:01.952+00:00","statement":{"source":"euvd","id":"EUVD-2025-201731","aliases":["CVE-2025-66490","GHSA-gm3x-23wp-hc2c"],"title":"Traefik is an HTTP reverse proxy and load balancer. For versions prior to 2.11.32 and 2.11.31 through 3.6.2, requests using PathPrefix, Path or PathRegex matchers can bypass path normalization. When Traefik uses path-based routing, requests…","description":"Traefik is an HTTP reverse proxy and load balancer. For versions prior to 2.11.32 and 2.11.31 through 3.6.2, requests using PathPrefix, Path or PathRegex matchers can bypass path normalization. When Traefik uses path-based routing, requests containing URL-encoded restricted characters (/, \\, Null, ;, ?, #) can bypass the middleware chain and reach unintended backends. For example, a request to http://mydomain.example.com/admin%2F could reach service-a without triggering my-security-middleware, bypassing security controls for the /admin/ path. This issue is fixed in versions 2.11.32 and 3.6.3.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N","score":6.9,"severity":null}],"references":["https://github.com/traefik/traefik/security/advisories/GHSA-gm3x-23wp-hc2c","https://github.com/traefik/traefik/releases/tag/v2.11.32","https://github.com/traefik/traefik/releases/tag/v3.6.4"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2025-201731","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Dec 9, 2025, 12:35:26 AM","dateUpdated":"Dec 9, 2025, 4:03:33 PM"},"relatedAdvisories":[{"id":"RHSA-2026:2456","title":"Red Hat Security Advisory: Red Hat OpenShift Dev Spaces 3.26.0 Release.","vulnerabilityIds":["CVE-2024-25621","CVE-2025-12816","CVE-2025-15284","CVE-2025-52881","CVE-2025-58183","CVE-2025-61729","CVE-2025-64756","CVE-2025-65945","CVE-2025-66031","CVE-2025-66418","CVE-2025-66471","CVE-2025-66490","CVE-2026-21441","CVE-2026-22029"]},{"id":"openSUSE-SU-2026:10143-1","title":"traefik2-2.11.35-1.1 on GA media","vulnerabilityIds":["CVE-2025-54386","CVE-2025-58181","CVE-2025-66490","CVE-2026-22045"]},{"id":"openSUSE-SU-2026:10020-1","title":"traefik-3.6.6-1.1 on GA media","vulnerabilityIds":["CVE-2025-66490","CVE-2025-66491"]}],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2025-201731","identifiers":["EUVD-2025-201731","CVE-2025-66490","GHSA-gm3x-23wp-hc2c"]},"retained":false,"historicalAffected":[]},{"revision":"40291f910ed14ef3bf1fca39ed1e5b76","observedAt":"2026-10-25T03:17:36.152+00:00","statement":{"source":"nvd","id":"CVE-2025-66490","aliases":[],"title":"Traefik is an HTTP reverse proxy and load balancer. For versions prior to 2.11.32 and 2.11.31 through 3.6.2, requests using PathPrefix, Path or PathRegex matchers can bypass path normalization. When Traefik uses path-based routing, requests…","description":"Traefik is an HTTP reverse proxy and load balancer. For versions prior to 2.11.32 and 2.11.31 through 3.6.2, requests using PathPrefix, Path or PathRegex matchers can bypass path normalization. When Traefik uses path-based routing, requests containing URL-encoded restricted characters (/, \\, Null, ;, ?, #) can bypass the middleware chain and reach unintended backends. For example, a request to http://mydomain.example.com/admin%2F could reach service-a without triggering my-security-middleware, bypassing security controls for the /admin/ path. This issue is fixed in versions 2.11.32 and 3.6.3.","state":0,"publishedAt":"2025-12-09T01:16:55.54+00:00","modifiedAt":"2026-10-14T22:10:00.21+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","score":6.9,"severity":"MEDIUM"},{"system":"CVSS 3.1 · nvd@nist.gov · Primary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/traefik/traefik/releases/tag/v2.11.32","https://github.com/traefik/traefik/releases/tag/v3.6.4","https://github.com/traefik/traefik/security/advisories/GHSA-gm3x-23wp-hc2c"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-66490","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-436","NVD-CWE-noinfo"],"productCriteria":["cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*"],"sourceDates":{"published":"2025-12-09T01:16:55.540","lastModified":"2026-10-14T22:10:00.210"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2025-66490","identifiers":["CVE-2025-66490"]},"retained":false,"historicalAffected":[]},{"revision":"6dccf5206ff843ad91214b74d4aa99a4","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GHSA-gm3x-23wp-hc2c","aliases":["CVE-2025-66490","GO-2025-4206"],"title":"Path Normalization Bypass in Traefik Router + Middleware Rules","description":"## Impact\n\nThere is a potential vulnerability in Traefik managing the requests using a `PathPrefix`, `Path` or `PathRegex` matcher.\n\nWhen Traefik is configured to route the requests to a backend using a matcher based on the path; if the request path contains an encoded restricted character from the following set **('/', '\\', 'Null', ';', '?', '#')**, it’s possible to target a backend, exposed using another router, by-passing the middlewares chain.\n\n## Example\n\n```yaml\napiVersion: traefik.io/v1alpha1\nkind: IngressRoute\nmetadata:\n  name: my-service\nspec:\n  routes:\n    - match: PathPrefix(‘/admin/’)\n      kind: Rule\n      services:\n        - name: service-a\n          port: 8080\n      middlewares:\n        - name: my-security-middleware\n    - match: PathPrefix(‘/’)\n      kind: Rule\n      services:\n        - name: service-a\n          port: 8080\n```\n\nIn such a case, the request `http://mydomain.example.com/admin%2F` will reach the backend `service-a` without operating the middleware `my-security-middleware` and passing the security put in place for the `/admin/` path.\n\n## Patches\n\n- https://github.com/traefik/traefik/releases/tag/v2.11.32\n- https://github.com/traefik/traefik/releases/tag/v3.6.4\n\n## For more information\n\nIf you have any questions or comments about this advisory, please [open an issue](https://github.com/traefik/traefik/issues).\n\n<details>\n<summary>Original Description</summary>### Summary\nA vulnerability exists in Traefik’s path matching logic that allows attackers to bypass access-control middleware (e.g., blocking rules) by using URL-encoded paths. I found this vulnerability while playing PwnSec CTF 2025 with my team @0xL4ugh\n\n### Details\nTraefik evaluates router rules before decoding or normalizing the request path, but forwards the request after decoding to the backend service. As a result, routes meant to block access to sensitive endpoints (such as internal, beta, or admin endpoints) can be trivially bypassed.\n\n### PoC\nTraefik configuration used in this issue :\n```[http.routers.flask-router-report-deny]\n  entryPoints = [\"web\"]\n  rule = \"PathPrefix(`/report_note`)\"\n  priority = 10\n  middlewares = [\"block-access\"]\n  service = \"flask-service\"\n\n[http.middlewares.block-access.replacePathRegex]\n  regex = \".*\"\n  replacement = \"/blocked\"\n```\nThe intention is to block all access to /report_note.\n\nHowever, the following request bypasses the block:\n```\nPOST /%2freport_note HTTP/1.1\nHost: localhost:62814\n\n\n```\n### Impact\nAccess Control Bypass:\nAny endpoint intended to be blocked (e.g., admin/debug/beta APIs) can be accessed by URL-encoding slashes or other characters.\n\nThis could lead to:\n\n- Unauthorized access to restricted endpoints\n- Execution of protected internal functionality\n- Potential privilege escalation\n- Bypass of security policies enforced via Traefik routing rules\n</details>","state":0,"publishedAt":"2025-12-08T16:42:30+00:00","modifiedAt":"2026-04-16T02:14:32.8352551+00:00","affected":[{"ecosystem":"Go","name":"github.com/traefik/traefik","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"last_affected","version":"1.7.34"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/traefik/traefik/v2","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"2.11.32"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/traefik/traefik/v3","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"3.6.3"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/traefik/traefik/security/advisories/GHSA-gm3x-23wp-hc2c","https://nvd.nist.gov/vuln/detail/CVE-2025-66490","https://github.com/traefik/traefik","https://github.com/traefik/traefik/releases/tag/v2.11.32","https://github.com/traefik/traefik/releases/tag/v3.6.4"],"sourceUrl":"https://github.com/advisories/GHSA-gm3x-23wp-hc2c","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-gm3x-23wp-hc2c","identifiers":["GHSA-gm3x-23wp-hc2c","CVE-2025-66490","GO-2025-4206"]},"retained":false,"historicalAffected":[]},{"revision":"2dde11c48691484da82bbe1258a58608","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GO-2025-4206","aliases":["CVE-2025-66490","GHSA-gm3x-23wp-hc2c"],"title":"Path Normalization Bypass in Traefik Router + Middleware Rules in github.com/traefik/traefik","description":"Path Normalization Bypass in Traefik Router + Middleware Rules in github.com/traefik/traefik","state":0,"publishedAt":"2025-12-15T19:37:35+00:00","modifiedAt":"2026-04-16T02:14:30.441752+00:00","affected":[{"ecosystem":"Go","name":"github.com/traefik/traefik","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/traefik/traefik/v2","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"2.11.32"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/traefik/traefik/v3","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"3.6.3"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[],"references":["https://github.com/traefik/traefik/security/advisories/GHSA-gm3x-23wp-hc2c","https://nvd.nist.gov/vuln/detail/CVE-2025-66490","https://github.com/traefik/traefik/releases/tag/v2.11.32","https://github.com/traefik/traefik/releases/tag/v3.6.4"],"sourceUrl":"https://osv.dev/vulnerability/GO-2025-4206","license":"OSV · upstream source license applies","key":"osv:GO-2025-4206","identifiers":["GO-2025-4206","CVE-2025-66490","GHSA-gm3x-23wp-hc2c"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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