The vulnerability of the intermediate software ForwardAuth in the reverse proxy server Containous Traefik allows a hacker to bypass authentication with invalid credentials.
🗓️ 12 May 2026 00:00:00Reported by FSTEC of Russia — Information Security Threat DatabaseType 
bdu_fstec🔗 bdu.fstec.ru👁 10 Views
| Reporter | Title | Published | Views | Family All 32 |
|---|---|---|---|---|
 | CVE-2026-39858 | 30 Apr 202620:26 | – | attackerkb |
 | CVE-2026-39858 | 30 Apr 202620:26 | – | alpinelinux |
 | CVE-2026-39858 | 24 Apr 202613:35 | – | circl |
 | Traefik 安全漏洞 | 30 Apr 202600:00 | – | cnnvd |
 | CVE-2026-39858 | 30 Apr 202620:26 | – | cve |
 | CVE-2026-39858 Traefik: Forwarded alias spoofing top pre-auth decision bypass | 30 Apr 202620:26 | – | cvelist |
 | EUVD-2026-26427 | 30 Apr 202620:26 | – | euvd |
 | Traefik: Pre-authentication decision bypass due to forwarded alias spoofing | 24 Apr 202616:32 | – | github |
| Traefik: Incomplete fix for CVE-2026-33433 + CVE-2026-39858 cross-cohort: headerField underscore-variant identity spoofing in BasicAuth / DigestAuth / ForwardAuth | 6 Aug 202616:53 | – | github |
 | Traefik < 2.11.43 / 3.x < 3.6.14 Multiple Vulnerabilities | 2 May 202600:00 | – | nessus |
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12 May 2026 00:00Current
5.8Medium risk
Vulners AI Score5.8
CVSS 29.4
CVSS 310
EPSS0.00479