Race condition in Traefik - #VU153914
Published: October 7, 2026
Vulnerability identifier: #VU153914
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-362
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper synchronization of shared reads and writes in Traefik's per-connection sticky round tripper when handling concurrent HTTP/2 or HTTP/3 requests over a single client connection. A remote attacker can send concurrent requests that race on the shared round tripper slot to cause a denial of service.
Exploitation requires a backend that responds with a WWW-Authenticate: NTLM or Negotiate challenge.
Affected software
Traefik
Remediation
Install security update from vendor's website.
Traefik - addressed in versions 2.11.58, 3.7.14