---
id: CVE-2026-119574
title: Traefik 3.2.0 before 3.7.15 FastProxy Data Race Denial of Service
summary: >-
  Traefik from 3.2.0 before 3.7.15 contains a data race in the experimental
  FastProxy that allows unauthenticated attackers to crash the process by
  abusing HTTP/1 protocol upgrades. Attackers can repeatedly open and abort
  upgraded connecti…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-567
vendor: traefik
product: traefik
affected:
  - traefik >= 3.2.0 < 3.7.15
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-30T15:17:03.547846Z'
published: '2026-10-30'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T15:17:13.625Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-119574'
references:
  - url: 'https://github.com/traefik/traefik/security/advisories/GHSA-ww7c-q3mv-xx22'
    label: GitHub Security Advisory (GHSA-ww7c-q3mv-xx22)
  - url: >-
      https://www.vulncheck.com/advisories/traefik-3.2.0-before-3.7.15-fastproxy-data-race-denial-of-service
    label: >-
      VulnCheck Advisory: Traefik 3.2.0 before 3.7.15 FastProxy Data Race Denial
      of Service
tags:
  - cve.org
epss: 0.00284
epssPercentile: 0.21009
ingestedAt: '2026-11-05T16:07:30.402Z'
---

## Overview

Traefik from 3.2.0 before 3.7.15 contains a data race in the experimental FastProxy that allows unauthenticated attackers to crash the process by abusing HTTP/1 protocol upgrades. Attackers can repeatedly open and abort upgraded connections such as WebSocket, corrupting the unsynchronized shared bufio.Reader and triggering an unrecovered panic that terminates Traefik.

## Affected

- `traefik >= 3.2.0 < 3.7.15`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.