CVE-2026-40912

HIGH EPSS 42.9%
Published Apr 30, 20262mo ago · Modified Jun 17, 20261w ago
7.8 CVSS 4.0
High
Find Similar
Published Apr 30, 2026 2mo ago
Last Modified Jun 17, 2026 1w ago

Description

Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a high severity authentication bypass vulnerability in Traefik's StripPrefixRegex middleware when used in combination with ForwardAuth, BasicAuth, or DigestAuth. The middleware matches the regex against the decoded URL path but uses the resulting byte length to slice the percent-encoded raw path. When a dot (or multiple dots) appears in the prefix portion of the URL, the raw path after stripping becomes a dot-segment (e.g. /./admin/secret). ForwardAuth receives this dot-segment path in X-Forwarded-Uri, which does not match the protected path patterns and therefore allows the request through. The backend then normalizes the dot-segment to the real path per RFC 3986 and serves the protected content An unauthenticated attacker can exploit this against any backend that performs dot-segment normalization. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.

CVSS Details

Base Score
7.8
Exploitability
—
Impact
—
Vector string
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/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
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
42.9% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 1

CWE-706

Affected Products 6

VendorProductVersionRange
traefiktraefik* <2.11.43
traefiktraefik*≥3.0.0  –  <3.6.14
traefiktraefik3.7.0any
traefiktraefik3.7.0any
traefiktraefik3.7.0any
traefiktraefik3.7.0any

References 4

  • github.com https://github.com/traefik/traefik/releases/tag/v2.11.43
    ProductRelease Notes
  • github.com https://github.com/traefik/traefik/releases/tag/v3.6.14
    ProductRelease Notes
  • github.com https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2
    ProductRelease Notes
  • github.com https://github.com/traefik/traefik/security/advisories/GHSA-6jwx-7vp4-9847
    ExploitPatchVendor Advisory

Remediation

  • github.com https://github.com/traefik/traefik/security/advisories/GHSA-6jwx-7vp4-9847
    ExploitPatchVendor Advisory