Data Race Vulnerability in Traefik by Containing Unauthenticated Attack Process Crashes
CVE-2026-119574

8.2HIGH

Key Information:

Vendor

Traefik

Status
Traefik
Vendor
CVE Published:
30 October 2026

What is CVE-2026-119574?

A vulnerability exists in Traefik versions prior to 3.7.15, particularly in the experimental FastProxy feature. This vulnerability is caused by a data race that allows unauthenticated attackers to exploit the HTTP/1 protocol upgrades. By repeatedly opening and aborting upgraded connections like WebSocket, attackers can corrupt the unsynchronized shared bufio.Reader. This leads to an unrecovered panic, ultimately causing the Traefik process to crash. Users are advised to upgrade to the latest version to mitigate this risk.

Affected Version(s)

traefik 3.2.0 < 3.7.15

traefik 3.7.15

References

https://github.com/traefik/traefik/security/advisories/GH...
vendor-advisory
https://www.vulncheck.com/advisories/traefik-3.2.0-before...
third-party-advisory

CVSS V4

Score:
8.2
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.