CVE-2026-71324
published 2026-08-06CVE-2026-71324: Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.53, 3.6.24, and 3.7.9, Traefik's default HTTP reverse proxy forwards a plain…
PriorityP344high7CVSS 4.0
AVNACLATPPRNUINVCNVINVANSCHSIHSANEXCRXIRXARXMAVXMACXMATXMPRXMUIXMVCXMVIXMVAXMSCXMSIXMSAXSXAUXRXVXREXUX
EPSS
0.55%
44.3th percentile
Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.53, 3.6.24, and 3.7.9, Traefik's default HTTP reverse proxy forwards a plain HTTP/2 or HTTP/3 CONNECT request and its body to an HTTP/1.1 upstream through a shared net/http.Transport. When the upstream answers the CONNECT with a keep-alive non-2xx response and does not drain the body, Traefik returns the desynchronized backend socket to its shared pool and reuses it for other clients. An unauthenticated attacker can use this behavior to make a different client read the attacker's smuggled response, which can include authenticated or private content from another request. The ForwardAuth middleware with forwardBody true and preserveRequestMethod true can re-issue a CONNECT with the buffered body attached, exposing the auth-client pool to the same desynchronization. This issue is fixed in 2.11.53, 3.6.24, and 3.7.9.
Affected
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| devspaces | traefik-rhel9 | — | — |
| github.com | traefik_traefik | 0 – 1.7.34 | — |
| github.com | traefik_traefik_v2 | >= 0 < 2.11.53 | 2.11.53 |
| github.com | traefik_traefik_v3 | >= 0 < 3.6.24 | 3.6.24 |
| github.com | traefik_traefik_v3 | >= 3.7.0 < 3.7.9 | 3.7.9 |
| traefik | traefik | < 2.11.53 | 2.11.53 |
| traefik | traefik | — | — |
| traefik | traefik | — | — |
CVSS provenance
nvdv4.07.0HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/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_redhat7.0HIGH
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VulDB
Traefik up to 2.11.52/3.6.23/3.7.8 Reverse Proxy improper synchronization
vuldb·2026-08-07·CVSS 7.0
CVE-2026-71324 [HIGH] Traefik up to 2.11.52/3.6.23/3.7.8 Reverse Proxy improper synchronization
A vulnerability, which was classified as critical, was found in Traefik up to 2.11.52/3.6.23/3.7.8. Affected by this vulnerability is an unknown functionality of the component Reverse Proxy. The manipulation results in improper synchronization.
This vulnerability is reported as CVE-2026-71324. The attack can be launched remotely. No exploit exists.
You should upgrade the affected component.
GHSA
Traefik: Cross-user response poisoning via proxied CONNECT on Traefik's shared backend keep-alive pool
ghsa·2026-08-06
CVE-2026-71324 [HIGH] CWE-444 Traefik: Cross-user response poisoning via proxied CONNECT on Traefik's shared backend keep-alive pool
Traefik: Cross-user response poisoning via proxied CONNECT on Traefik's shared backend keep-alive pool
## Summary
There is a critical vulnerability in Traefik's default HTTP reverse proxy that leads to unauthenticated cross-user response poisoning. When a client opens an HTTP/2 or HTTP/3 `CONNECT` request, Traefik forwards it — body included — to an HTTP/1.1 upstream over a shared `net/http.Transport`. If the upstream answers the CONNECT with a keep-alive non-2xx response without draining the body, the now-desynchronized backend socket is returned to Traefik's shared connection pool and reused for other clients, letting an attacker make a different client read a response the attacker smuggled — which may be another user's authenticated or private content. The entrypoint's `sanitizePath`
Red Hat
github.com/traefik/traefik: Traefik: Information disclosure via response poisoning in shared backend pool
vendor_redhat·2026-08-06·CVSS 7.0
CVE-2026-71324 [HIGH] CWE-444 github.com/traefik/traefik: Traefik: Information disclosure via response poisoning in shared backend pool
github.com/traefik/traefik: Traefik: Information disclosure via response poisoning in shared backend pool
Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.53, 3.6.24, and 3.7.9, Traefik's default HTTP reverse proxy forwards a plain HTTP/2 or HTTP/3 CONNECT request and its body to an HTTP/1.1 upstream through a shared net/http.Transport. When the upstream answers the CONNECT with a keep-alive non-2xx response and does not drain the body, Traefik returns the desynchronized backend socket to its shared pool and reuses it for other clients. An unauthenticated attacker can use this behavior to make a different client read the attacker's smuggled response, which can include authenticated or private content from another request. The ForwardAuth middleware with forwar
No detection rules found.
No public exploits indexed.
https://github.com/traefik/traefik/commit/04d36f28e4eae7535e96a6351dd9f7bfb48a30e7https://github.com/traefik/traefik/commit/0807b6d5dd1da8b2f7f4076ea2392b5437bf2ab0https://github.com/traefik/traefik/commit/94a7508817d180f0ab2f1eae93df48d4ab19eccehttps://github.com/traefik/traefik/pull/13542https://github.com/traefik/traefik/pull/13543https://github.com/traefik/traefik/pull/13556https://github.com/traefik/traefik/releases/tag/v2.11.53https://github.com/traefik/traefik/releases/tag/v3.6.24https://github.com/traefik/traefik/releases/tag/v3.7.9https://github.com/traefik/traefik/security/advisories/GHSA-3ccp-42pg-hgv6
2026-08-06
Published