CVE-2026-26998
MEDIUM
GHSA-fw45-f5q2-2p4x
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:H/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 the ForwardAuth middleware responses. When Traefik is configured to use the ForwardAuth middleware, the response body from the authentication server is read entirely into memory without any size limit. There is no maxResponseBodySize configuration to restrict the amount of data read from the authentication server response. If the authentication server returns an unexpectedly large or unbounded response body, Traefik will allocate unlimited memory, potentially causing an out-of-memory (OOM) condition that crashes the process. This results in a denial of service for all routes served by the affected Traefik instance. This issue has been patched in versions 2.11.38 and 3.6.9.
Analysis
Traefik versions prior to 2.11.38 and 3.6.9 fail to limit memory allocation when processing ForwardAuth middleware responses, allowing a malicious or compromised authentication server to trigger unbounded memory consumption. An attacker controlling the auth server can return an arbitrarily large response body that causes the Traefik process to exhaust available memory and crash, resulting in denial of service for all proxied routes. …
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Remediation
Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Vendor patch is available.
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