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.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact High

Subsequent System Integrity Impact Low

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00068.

Exploitation none

Automatable yes

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
traefik traefik affected
Version Status Constraints
< 2.11.43 affected —
>= 3.0.0-beta1, < 3.6.14 affected —
>= 3.7.0-ea.1, < 3.7.0-rc.2 affected —

Configuration 1 [-]

OR cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea1:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea2:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea3:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:rc1:*:*:*:*:*:*

No data.

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Vendors Products
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Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-6jwx-7vp4-9847 Traefik has an StripPrefixRegex Middleware Authorization Bypass via Path/RawPath Desync
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/traefik/traefik/releases/tag/v2.11.43 cve-icon cve-icon cve-icon
https://github.com/traefik/traefik/releases/tag/v3.6.14 cve-icon cve-icon cve-icon
https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2 cve-icon cve-icon cve-icon
https://github.com/traefik/traefik/security/advisories/GHSA-6jwx-7vp4-9847 cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-40912 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-40912 cve-icon
History

Sat, 09 May 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-22
References
Metrics threat_severity

None

 threat_severity

Important

Fri, 01 May 2026 17:45:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea1:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea2:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea3:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:rc1:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N'}

Fri, 01 May 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Thu, 30 Apr 2026 21:45:00 +0000

Type Values Removed Values Added
First Time appeared Traefik
Traefik traefik
Vendors & Products Traefik
Traefik traefik

Thu, 30 Apr 2026 20:45:00 +0000

Type Values Removed Values Added
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.
Title Traefik: StripPrefixRegex auth bypass via Path/RawPath desync
Weaknesses CWE-706
References
Metrics cvssV4_0

{'score': 7.8, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-01T14:54:06.078Z

Reserved: 2026-04-15T16:37:22.768Z

Link: CVE-2026-40912

cve-icon Vulnrichment

Updated: 2026-05-01T14:53:40.695Z

cve-icon NVD

Status : Analyzed

Published: 2026-04-30T21:16:32.740

Modified: 2026-05-01T17:42:32.060

Link: CVE-2026-40912

cve-icon Redhat

Severity : Important

Publid Date: 2026-04-30T20:38:21Z

Links: CVE-2026-40912 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-05-09T02:15:06Z

Weaknesses