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CVE-2026-88878— Traefik v2.8.2 through v3.6 HTTP/3 Timeout Bypass

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 是一款 HTTP 反向代理和负载均衡器。在 v2.8.2 至 v2.11.55 以及 v3.0.0 至 v3.7.11 的版本中， 配置项——特别是默认启用且超时时间为 60 秒的 ——未应用于 HTTP/3 请求路径。 是施加于底层 TCP 连接的截止时间（deadline），而该机制无法应用于 QUIC 流；此外，Traefik 的 HTTP/3 服务器在构建时未设置任何超时机制。因此，在启用了 HTTP/3 的入口点上，未认证的远程客户端可以通过缓慢地逐字节发送请求体数据，使请求无限期保持打开

CVSS 5.3 · Medium

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-88878

Vulnerability Information
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Vulnerability Title
Traefik v2.8.2 through v3.6 HTTP/3 Timeout Bypass
Source: CVE Program / CVE List V5
Vulnerability Description
Traefik is an HTTP reverse proxy and load balancer. In versions >= v2.8.2 through <= v2.11.55 and >= v3.0.0 through <= v3.7.11, the entryPoints.<name>.transport.respondingTimeouts settings — notably readTimeout, which is enabled by default at 60s — are not applied to the HTTP/3 request path. readTimeout is enforced as a deadline on the underlying TCP connection, which cannot be applied to a QUIC stream, and Traefik's HTTP/3 server is constructed without any timeout. As a result, on entry points with HTTP/3 enabled, an unauthenticated remote client that trickles request body bytes can hold a request open indefinitely and, with it, one upstream connection per request, exhausting bounded backend connection pools and causing denial of service. The issue was introduced in v2.8.2 when a quic-go API change removed the embedded http.Server that carried these timeouts. Fixed in v2.11.56 and v3.7.12.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
traefik traefik 2.8.2 ~ 3.7.13 -
traefik traefik 3.0.0 ~ 3.7.13 -

II. Public POCs for CVE-2026-88878

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III. Intelligence Information for CVE-2026-88878

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Vendor Advisories for CVE-2026-88878 (2)

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-2026-88004 7.0 HIGH Traefik entrypoint header-name sanitization bypassed via request trailers
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-2026-88011 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-770

V. Comments for CVE-2026-88878

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