CVE-2026-88007
published 2026-09-10CVE-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…
PriorityP357critical9.1CVSS 3.1
AVNACLPRNUINSUCHIHAN
EPSS
0.60%
48.0th percentile
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.
Affected
7 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| devspaces | traefik-rhel9 | — | — |
| github.com | traefik_traefik_v2 | >= 2.11.0 < 2.11.57 | 2.11.57 |
| github.com | traefik_traefik_v3 | >= 3.0.0 < 3.7.13 | 3.7.13 |
| traefik | traefik | — | — |
| traefik | traefik | — | — |
| traefik | traefik | >= 2.8.2 < 2.11.56 | 2.11.56 |
| traefik | traefik | >= 3.0.0 < 3.7.12 | 3.7.12 |
CVSS provenance
nvdv3.19.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
nvdv4.09.1CRITICALCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/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:X/V:X/RE:X/U:X
vendor_redhat9.1CRITICAL
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Red Hat
github.com/traefik/traefik: Traefik HTTP/3 Backend NTLM Connection Reuse
vendor_redhat·2026-09-10·CVSS 9.1
CVE-2026-88007 [CRITICAL] CWE-863 github.com/traefik/traefik: Traefik HTTP/3 Backend NTLM Connection Reuse
github.com/traefik/traefik: Traefik HTTP/3 Backend NTLM Connection Reuse
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.
A flaw in Traefik's HTTP/3 ConnContext allows unauthenticated remote attackers to bypass authentication on backend
VulDB
Traefik prior 2.11.57/3.7.13 HTTP/3 Entrypoint information disclosure (EUVD-2026-75544)
vuldb·2026-09-11·CVSS 9.1
CVE-2026-88007 [CRITICAL] Traefik prior 2.11.57/3.7.13 HTTP/3 Entrypoint information disclosure (EUVD-2026-75544)
A vulnerability labeled as problematic has been found in Traefik. Affected is an unknown function of the component HTTP/3 Entrypoint. Such manipulation leads to information disclosure.
This vulnerability is traded as CVE-2026-88007. The attack may be launched remotely. There is no exploit available.
The affected component should be upgraded.
GHSA
Traefik HTTP/3 Backend NTLM Connection Reuse
ghsa·2026-09-10
CVE-2026-88007 [CRITICAL] CWE-287 Traefik HTTP/3 Backend NTLM Connection Reuse
Traefik HTTP/3 Backend NTLM Connection Reuse
## Summary
Traefik's HTTP/3 request path did not initialize the connection-scoped backend transport holder that isolates connection-bound NTLM and Negotiate (Kerberos) authentication on the HTTP/1.1 and HTTP/2 paths. The HTTP/3 entrypoint reuses the HTTPS handler chain and reaches the same backend round-tripper, but its `ConnContext` never called `service.AddTransportOnContext`, so `kerberosRoundTripper` fell back to the shared backend transport instead of a per-frontend-connection pool. On a route served over HTTP/3 to a backend that binds identity to a persistent connection via NTLM or Negotiate, an unrelated HTTP/3 client could be assigned a backend connection already authenticated as a victim and inherit that identity, reading victim-only
No detection rules found.
No public exploits indexed.
https://github.com/traefik/traefik/commit/ff39c47d7459dec9cd8de63c1a4e7aa7315bdc1chttps://github.com/traefik/traefik/pull/13812https://github.com/traefik/traefik/releases/tag/v2.11.57https://github.com/traefik/traefik/releases/tag/v3.7.13https://github.com/traefik/traefik/security/advisories/GHSA-qqjf-53cj-pwvv
2026-09-10
Published