Improper Handling of Case Sensitivity in Traefik - CVE-2026-54763
Published: July 3, 2026
Vulnerability identifier: #VU136877
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-54763
CWE-ID: CWE-178
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Containous
Affected software:
Traefik
Traefik
Detailed vulnerability description
The vulnerability allows a remote user to spoof identity or authorization context.
The vulnerability exists due to improper handling of case sensitivity in BasicAuth, DigestAuth, ForwardAuth, and ingress-nginx snippet authResponseHeaders handling when processing underscore-variant identity headers. A remote user can send a specially crafted request with underscore-variant headers to spoof identity or authorization context.
In the ForwardAuth authResponseHeaders path, exploitation does not require credentials.
How to mitigate CVE-2026-54763
Install security update from vendor's website.