GHSA-v67p-phpq-fc8x: github.com/traefik/traefik/v3 (CVE-2026-88004)

Package	Ecosystem	Affected	Fixed in
github.com/traefik/traefik/v3	Go	>=3.2.0, <3.7.13	3.7.13

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Traefik v3 versions from 3.2.0 before 3.7.13 let an unauthenticated client smuggle sanitized header names, such as X_Auth_User or X-Forwarded-Prefix, through HTTP trailers, bypassing the entrypoint's header-name sanitization. When a body-buffering middleware such as retry or buffering is in the chain, the attacker-chosen trailer value can reach the backend, and backends that merge trailers into headers may act on it. Upgrade to Traefik v3.7.13, which is the fix; end-of-life v3 lines have no separate fix and need to move to v3.7.13.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.0	High	4.0	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	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0045, the 39th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:13 UTC First seen by agentprime
31 Oct 2026, 14:13 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.