6.9

CVE-2025-66490: Traefik doesn't Prevent Path Normalization Bypass in Router + Middleware Rules

Analyzed
AliasesCGA-5fgx-qxgf-qvq5CGA-8gqc-pj2q-x2w6CGA-rjxm-cvg8-44mv
Published 09-12-2025Last modified 09-12-2025

Vulnerability summary

CVE-2025-66490 is a medium (CVSS 6.9) Interpretation Conflict vulnerability in traefik. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 38.2% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Routine

Not severe (CVSS 6.9, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
6.9/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.44%
0%100%
Low · +0.07 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1github

Advisory lineage

Upstream 0 · Downstream 4 · Related 5
OPENSUSE-SU-2026:10020-1OPENSUSE-SU-2026:10143-1OPENSUSE-SU-2026:21483-1SUSE-SU-2026:0037-1CGA-M4QP-GW68-X255

Timeline

  1. 09-12-2025
    PublishedVulnerability first disclosed.
  2. 09-12-2025
    Last modifiedVulnerability information updated.

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

6 scores · 5 sources · 2 versions

EPSS trend

Probability

0.44%

Chance of exploitation in the next 30 days

Percentile

38%

Versus all other CVEs

30-day change

Increase +0.07 pp

From 0.37% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • githubUnverified

    Traefik

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard3 products
  • traefik-3.4All versions (No fix recorded)
  • traefik-3.5All versions (No fix recorded)
  • traefik-fips-3.5All versions (No fix recorded)
Github.com/traefik/traefik2 products
  • v2< 2.11.32
  • v3< 3.6.3
Github.com/traefik1 product
  • traefik≤ 1.7.34 | All versions (No fix recorded)
Traefik1 product
  • traefikgithub.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
Wolfi1 product
  • traefik-3.4All versions (No fix recorded)

5 vendors · 8 products

References

6 links