Vulnerability in Traefik
CVE-2025-66490
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.
EPSS: 0.004 (27.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
Affected products
- Traefik — versions github.com/traefik/traefik/v3 < 3.6.3, github.com/traefik/traefik/v2 < 2.11.32, github.com/traefik/traefik <= 1.7.34
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2025-66490?
- CVE-2025-66490 is a medium-severity vulnerability in Traefik, classified under CWE-436. CVSS score: 6.5/10. Published 2025-12-09.
- How severe is CVE-2025-66490?
- Medium severity. CVSS v3 base score is 6.5 out of 10.