CVE-2025-66490

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.

CVSS Metrics

• v4.0•MEDIUM•Score: 6.9CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
• v4.0•MEDIUM•Score: 6.9CVSS: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
• v3.1•MEDIUM•Score: 6.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS Trends

Current EPSS score: 0.02%• Percentile: 5%

Techniques & Countermeasures

• CWE-436•Interpretation Conflict

  Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.

Affected Systems

• github.com/traefik•traefik

  ≤ 1.7.34 | all

• github.com/traefik/traefik•v2

  < 2.11.32

• github.com/traefik/traefik•v3

  < 3.6.3

• traefik•traefik

  github.com/traefik/traefik/v3 < 3.6.3 | github.com/traefik/traefik/v2 < 2.11.32 | github.com/traefik/traefik <= 1.7.34 | < 2.11.32 | ≥ 3.0.0, < 3.6.3

References (5)

• 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
• https://nvd.nist.gov/vuln/detail/CVE-2025-66490
• https://github.com/traefik/traefik