Auth bypass in Traefik
CVE-2026-88007
Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13, the HTTP/3 entrypoint ConnContext does not call service.AddTransportOnContext, so kerberosRoundTripper uses a shared backend transport instead of a transport dedicated to each frontend connection. With HTTP/3 enabled, a backend using connection-bound NTLM or Negotiate authentication, and backend keep-alive, an unrelated client can reuse a backend connection authenticated for a victim, read victim-only data, and act as that victim without the victim credentials. This issue is fixed in 2.11.57 and 3.7.13.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.006 (48.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 48.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
- Traefik — versions >= 2.11.0, < 2.11.57, >= 3.0.0, < 3.7.13
Weakness classification (CWE)
References
- github.com/traefik/traefik/security/advisories/GHSA-qqjf-53cj-pwvv (Patch, Vendor Advisory)
- github.com/traefik/traefik/pull/13812 (Patch, Issue Tracking)
- github.com/traefik/traefik/commit/ff39c47d7459dec9cd8de63c1a4e7aa7315bdc1c (Patch)
- github.com/traefik/traefik/releases/tag/v2.11.57 (Release Notes)
- github.com/traefik/traefik/releases/tag/v3.7.13 (Release Notes)
Frequently asked questions
- What is CVE-2026-88007?
- CVE-2026-88007 is a critical-severity vulnerability in Traefik, classified under Improper Authentication. CVSS score: 9.1/10. Published 2026-09-10.
- How severe is CVE-2026-88007?
- Critical severity. CVSS v3 base score is 9.1 out of 10.