Vulnerability · Published Mar 5, 2026 · Assigned by GitHub_M
CVE-2026-26998Traefik: unbounded io.ReadAll on auth server response body causes OOM denial of service(DOS)
Medium 4.4
In plain English
A medium-severity resource allocation without limits in traefik from traefik. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/traefik/traefik | no fix listed | GO-2026-4593 |
| Go | github.com/traefik/traefik/v2 | 2.11.38 | GHSA-fw45-f5q2-2p4x |
| Go | github.com/traefik/traefik/v2 | 2.11.38 | GO-2026-4593 |
| Go | github.com/traefik/traefik/v3 | 3.6.9 | GHSA-fw45-f5q2-2p4x |
| Go | github.com/traefik/traefik/v3 | 3.6.9 | GO-2026-4593 |
Affected products (as reported)
Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/traefik/traefik/security/advisories/GHSA-fw45-f5q2-2p4x x_refsource_CONFIRM
- https://github.com/traefik/traefik/releases/tag/v2.11.38 x_refsource_MISC
- https://github.com/traefik/traefik/releases/tag/v3.6.9 x_refsource_MISC