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certfr-2026-avi-0490 — De multiples vulnérabilités ont été découvertes dans Traefik. Elles permettent à un attaquant de provoquer une atteinte…

certfr-2026-avi-0490

CLEANSTART-2026-HD64585 — Security fix for CVE-2026-41263 applied in: forecastle 1.0.159-r1

Affected: CleanStart: forecastle

Security vulnerability affects the forecastle package. This issue is resolved in later releases. See references for vulnerability details.

EUVD-2026-308169

fkie_cve-2026-41263

Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a timing side-channel vulnerability in Traefik's BasicAuth middleware that allows an attacker to enumerate valid usernames through response-time differences. The variable intended to hold a constant-time fallback secret always resolves to an empty string, causing the constant-time comparison to short-circuit in microseconds rather than performing a full bcrypt evaluation. This restores the original timing oracle and makes it possible to distinguish existing users from non-existing ones by measuring authentication response times. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.

GHSA-6x2q-h3cr-8j2h — Traefik: A timing side-channel vulnerability allows for valid username enumeration via BasicAuth middleware

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

## Summary

There is a timing side-channel vulnerability in Traefik's BasicAuth middleware that allows an attacker to enumerate valid usernames through response-time differences.

The variable intended to hold a constant-time fallback secret always resolves to an empty string, causing the constant-time comparison to short-circuit in microseconds rather than performing a full bcrypt evaluation. This restores the original timing oracle and makes it possible to distinguish existing users from non-existing ones by measuring authentication response times.

## Patches

- https://github.com/traefik/traefik/releases/tag/v2.11.43 - https://github.com/traefik/traefik/releases/tag/v3.6.14 - https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2

## 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>

# BasicAuth Timing Regression: CVE-2026-32595 Fix Is a No-Op Due to Map Key/Value Confusion

## TL;DR

The patch for CVE-2026-32595 is a no-op. Line 49 of `basic_auth.go` has a map key/value confusion that makes `notFoundSecret` always `""`. The "constant time" fallback calls `goauth.CheckSecret(password, "")`, which fast-fails in ~1us instead of running bcrypt (~60ms).

## Evidence (HEAD `786f7192e`, 2026-04-09)

Black-box PoC against live traefik binary on port 28080:

| bucket | n | median | min | |-------…

openSUSE-SU-2026:10697-1 — traefik-3.6.15-1.1 on GA media

traefik-3.6.15-1.1 on GA media