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Vulnerability record · CVE-2026-40912 · published 30 April 2026

CVE-2026-40912: Traefik path traversal vulnerability

Traefik · Traefik

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.

7.8 CVSS 4.0 High EPSS 0.72% · top 47.9% CWE-706 · CWE-706CWE-22 · Path traversal
7.8CVSS 4.0 base score
0.72%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References, 1 tagged exploit
15 Jul 2026Last modified by NVD

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: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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/traefik/traefik/releases/tag/v2.11.43 ProductRelease Notes
https://github.com/traefik/traefik/releases/tag/v3.6.14 ProductRelease Notes
https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2 ProductRelease Notes
https://github.com/traefik/traefik/security/advisories/GHSA-6jwx-7vp4-9847 ExploitPatchVendor Advisory
https://access.redhat.com/errata/RHSA-2026:21772
https://access.redhat.com/security/cve/CVE-2026-40912
https://bugzilla.redhat.com/show_bug.cgi?id=2464229
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40912.json

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-40912), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.