CVE-2026-26999
HIGH
GHSA-xw98-5q62-jx94
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
3Description
Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.38 and 3.6.9, there is a potential vulnerability in Traefik managing TLS handshake on TCP routers. When Traefik processes a TLS connection on a TCP router, the read deadline used to bound protocol sniffing is cleared before the TLS handshake is completed. When a TLS handshake read error occurs, the code attempts a second handshake with different connection parameters, silently ignoring the initial error. A remote unauthenticated client can exploit this by sending an incomplete TLS record and stopping further data transmission, causing the TLS handshake to stall indefinitely and holding connections open. By opening many such stalled connections in parallel, an attacker can exhaust file descriptors and goroutines, degrading availability of all services on the affected entrypoint. This issue has been patched in versions 2.11.38 and 3.6.9.
Analysis
Traefik versions before 2.11.38 and 3.6.9 allow remote attackers to cause denial of service by sending incomplete TLS records to TCP routers, which causes the TLS handshake process to hang indefinitely while holding connections open. An unauthenticated attacker can exploit this by opening many stalled connections in parallel to exhaust file descriptors and goroutines, degrading or disabling the proxy service.
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Remediation
Within 24 hours: Identify all Traefik instances and their versions in production and non-production environments. Within 7 days: Apply vendor patches to upgrade to versions 2.11.38 or 3.6.9 or later across all infrastructure, starting with production systems. …
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