CVE-2026-26998 MEDIUM

CVE-2026-26998: Traefik: unbounded io.ReadAll on auth server response body causes OOM denial of service(DOS)

Vendor Traefik
Product traefik
Weakness CWE-770 · Uncontrolled resource consumption
Published March 5, 2026
Last update March 6, 2026

CVSS base score

4.4/10
Attack vector Network
Attack complexity High
Privileges required High
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 5, 2026 CVE published
March 6, 2026 Record updated