CVE-2026-40912
High · 8.2CVSS
8.2
EPSS
0.7%
Published
Apr 30, 2026
CISA due date
—
The record
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.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| openSUSE:Tumbleweed | traefik | 0 | 3.6.15-1.1 |
| openSUSE:Tumbleweed | traefik2 | 0 | 2.11.44-1.1 |
Related vulnerabilities
- CVE-2026-48491 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-53622 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-48020 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-44774 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-41181 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-41174 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-41263 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-35051 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik