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

Affected: traefik

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.

GHSA-46wh-3698-f2cx — Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)

Affected: Go: github.com/traefik/traefik/v2, Go: github.com/traefik/traefik/v3

## Summary

There is a potential vulnerability in Traefik due to its dependency on an affected version of gRPC-Go (CVE-2026-33186).

A remote, unauthenticated attacker can send gRPC requests with a malformed HTTP/2 `:path` pseudo-header omitting the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server routes such requests correctly, path-based authorization interceptors evaluate the raw non-canonical path and fail to match "deny" rules, allowing the request to bypass the policy entirely if a fallback "allow" rule is present.

## Patches

- https://github.com/traefik/traefik/releases/tag/v2.11.42 - https://github.com/traefik/traefik/releases/tag/v3.6.12 - https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3

## For more information

If there are any questions or comments about this advisory, please [open an issue](https://github.com/traefik/traefik/issues).

<details> <summary>Original Description</summary>

### Summary This CVE hits traefik until Version 3.6.11 and 2.11.41. gRPC-Go has an authorization bypass via missing leading slash in :path ### Details As described in https://github.com/advisories/GHSA-p77j-4mvh-x3m3 ### PoC Update library version in https://github.com/traefik/traefik/blob/67c64ed9b25fbb90f1086977a62827133a7aa01b/go.mod#L108 ### Impact Is described in https://github.com/advisories/GHSA-p77j-4mvh-x3m3

</details>

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Most recent entries from all

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

GHSA-46wh-3698-f2cx — Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)