CVE-2026-39858— Traefik: Forwarded alias spoofing top pre-auth decision bypass

Traefik: Forwarded alias spoofing top pre-auth decision bypass

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 high severity authentication bypass vulnerability in Traefik's ForwardAuth and snippet-based authentication middleware. Traefik's forwarded-header sanitization logic targets only canonical header names (e.g., X-Forwarded-Proto) and does not strip or normalize alias variants that use underscores instead of dashes (e.g., X_Forwarded_Proto). These unsanitized alias headers are forwarded intact to the authentication backend. When the backend normalizes underscore and dash header forms equivalently, an attacker can inject spoofed trust context — such as a trusted scheme or host — through the alias headers and bypass authentication on protected routes without valid credentials. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.

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使用欺骗进行的认证绕过

Traefik 安全漏洞

Traefik是Traefik开源的一款反向代理与负载均衡工具。 Traefik存在安全漏洞，该漏洞源于转发标头清理逻辑仅针对规范标头名称，未处理使用下划线替代破折号的别名变体，可能导致身份验证绕过。以下版本受到影响：2.11.43之前版本、3.6.14之前版本和3.7.0-rc.2之前版本。

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