CVSS 3.1
4.4 mediumCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:HCVE-2026-26998
Medium (4.4) in traefik traefik. EPSS 0.5% chance of exploitation in the next 30 days. Fixed in github.com/traefik/traefik/v2 2.11.38.
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.
Severity
- EPSS
- 0.5% chance of exploitation in the next 30 days; higher than 43% of CVEs (scores of 2026-10-31)
- CWE
- CWE-770
- Published
- Modified
- Record from
- the NVD, synced
Affected
- traefik:traefik
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-fw45-f5q2-2p4x | Go | github.com/traefik/traefik/v2 | <2.11.38 | 2.11.38 |
| GHSA-fw45-f5q2-2p4x | Go | github.com/traefik/traefik/v3 | <3.6.9 | 3.6.9 |
| GO-2026-4593 | Go | github.com/traefik/traefik | all versions | no fix published |
| GO-2026-4593 | Go | github.com/traefik/traefik/v2 | <2.11.38 | 2.11.38 |
| GO-2026-4593 | Go | github.com/traefik/traefik/v3 | <3.6.9 | 3.6.9 |