CVE-2025-32431: Traefik has a possible vulnerability with the path matchers

Impact

There is a potential vulnerability in Traefik managing the requests using a PathPrefix, Path or PathRegex matcher.

When Traefik is configured to route the requests to a backend using a matcher based on the path, if the URL contains a /../ in its path, it’s possible to target a backend, exposed using another router, by-passing the middlewares chain.

Example

yaml apiVersion: traefik.io/v1alpha1 kind: IngressRoute metadata: name: my-service spec: routes: - match: PathPrefix(‘/service’) kind: Rule services: - name: service-a port: 8080 middlewares: - name: my-middleware-a - match: PathPrefix(‘/service/sub-path’) kind: Rule services: - name: service-a port: 8080

In such a case, the request http://mydomain.example.com/service/sub-path/../other-path will reach the backend my-service-a without operating the middleware my-middleware-a unless the computed path is http://mydomain.example.com/service/other-path and should be computes by the first router (operating my-middleware-a).

Patches

- https://github.com/traefik/traefik/releases/tag/v2.11.24 - https://github.com/traefik/traefik/releases/tag/v3.3.6 - https://github.com/traefik/traefik/releases/tag/v3.4.0-rc2

Workaround

Add a PathRegexp rule to the matcher to prevent matching a route with a /../ in the path.

Example:

yaml match: PathPrefix(/service) && !PathRegexp((?:(/\.\./)+.))

For more information

If you have any questions or comments about this advisory, please open an issue.