Traefik's ACME TLS-ALPN fast path lacks timeouts and close on handshake stall

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-22045: 0.34% estimated exploitation activity in the next 30 days; percentile 27.84 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact There is a potential vulnerability in Traefik ACME TLS certificates' automatic generation: the ACME TLS-ALPN fast path can allow unauthenticated clients to tie up goroutines and file descriptors indefinitely when the ACME TLS challenge is enabled. A malicious client can open many connections, send a minimal ClientHello with acme-tls/1, then stop responding, leading to denial of service of the entrypoint. Patches - https://github.com/traefik/traefik/releases/tag/v2.11.35 - https://github.com/traefik/traefik/releases/tag/v3.6.7 For more information If you have any questions or comments about this advisory, please open an issue. <details <summaryOriginal Description</summary \[Security\] ACME TLS-ALPN fast path lacks timeouts and close on handshake stall Dear Traefik security team, We believe we have identified a resource-exhaustion issue in the ACME TLS-ALPN fast path that can allow unauthenticated clients to tie up goroutines and file descriptors indefinitely when the ACME TLS…

Published by the source

15 Jan 2026, 22:58 UTC

Last modified by the source

16 Jan 2026, 15:20 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cwjm-3f7h-9hwq

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# Patch Next advisory brief: CVE-2026-22045

Advisory: Traefik's ACME TLS-ALPN fast path lacks timeouts and close on handshake stall
IDs: CVE-2026-22045, GHSA-cwjm-3f7h-9hwq
Record: https://patchnext.com/advisories/cve-2026-22045 (revision 1, source checked 26 Oct 2026, 15:14 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/traefik/traefik/v3 3.6.7; github.com/traefik/traefik/v2 2.11.35. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/traefik/traefik/v3: affected <= 3.6.6; fixed in 3.6.7
- Go github.com/traefik/traefik/v2: affected <= 2.11.34; fixed in 2.11.35

## Suggested inspection (read-only)
- Go github.com/traefik/traefik/v3: check the installed version with your package manager.
- Go github.com/traefik/traefik/v2: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/traefik/traefik/v3, github.com/traefik/traefik/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cwjm-3f7h-9hwq (GitHub-reviewed advisory GHSA-cwjm-3f7h-9hwq lists affected ranges: Go github.com/traefik/traefik/v3 >=0 =0 <=2.11.34)

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