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CVE-2026-88004— Traefik entrypoint header-name sanitization bypassed via request trailers

Quick assessment

Affected
traefik traefik
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Traefik 是一个开源的 HTTP 反向代理和负载均衡器。从 3.2.0 到 3.7.13 版本中，Traefik 的入口点防御机制 、 和 仅检查请求头（ ），而未检查请求尾（ ）。这使得未认证的客户端可以通过 HTTP/1.1 分块传输的尾部和 HTTP/2 的尾部字段，提交一个别名或受信任的头部名称。 当重试（retry）或缓冲（buffering）中间件在反向代理克隆请求之前读取请求体时，攻击者控制的尾部值会到达后端。这些后端会将尾部字段合并到请求头命名空间中，从而绕过文档中所述的“删除”或“拒绝”行为

CVSS 7.0 · High
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I. Basic Information for CVE-2026-88004

Vulnerability Information
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Vulnerability Title
Traefik entrypoint header-name sanitization bypassed via request trailers
Source: CVE Program / CVE List V5
Vulnerability Description
Traefik is an open source HTTP reverse proxy and load balancer. From 3.2.0 until 3.7.13, Traefik entrypoint defenses aliasHeadersStrategy, underscoreHeadersStrategy, and forwardedHeaders inspect req.Header but not req.Trailer, allowing an unauthenticated client to submit an aliasing or trusted header name in an HTTP/1.1 chunked trailer or an HTTP/2 trailer. When the retry or buffering middleware reads the body before the reverse proxy clones the request, the attacker-controlled trailer value reaches a backend that merges trailers into the header namespace, bypassing the documented delete or reject behavior and potentially spoofing identity or forwarded routing data. This issue is fixed in 3.7.13.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
解释冲突
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
traefik traefik >= 3.2.0, < 3.7.13 -

II. Public POCs for CVE-2026-88004

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III. Intelligence Information for CVE-2026-88004

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Patches & Fixes for CVE-2026-88004 (2)

Vendor Advisories for CVE-2026-88004 (1)

Vendor Pages for CVE-2026-88004 (1)

Same Patch Batch · traefik · 2026-09-10 · 9 CVEs total

CVE-2026-88877 9.8 CRITICAL Traefik v3.7.0 Authentication Bypass via from-to-www-redirect
CVE-2026-88007 9.1 CRITICAL Traefik HTTP/3 Backend NTLM Connection Reuse
CVE-2026-88009 8.8 HIGH Traefik: Rootless HTTP/1 request-target routes as "/" but is forwarded verbatim, bypassing
CVE-2026-88008 7.0 HIGH Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CVE-2026-88879 5.3 MEDIUM Traefik before v2.11.56 Identity Spoofing via Header Alias
CVE-2026-88878 5.3 MEDIUM Traefik v2.8.2 through v3.6 HTTP/3 Timeout Bypass
CVE-2026-88011 5.3 MEDIUM Traefik: ForwardAuth identity spoofing via dot-form header alias
CVE-2026-88012 5.3 MEDIUM Traefik: respondingTimeouts.readTimeout is not applied to HTTP/3, leaving slow-body upload

IV. Related Vulnerabilities

Same product: traefik
Same vendor: traefik
Same weakness: CWE-436

V. Comments for CVE-2026-88004

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