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Advisory record · GHSA-7r4p-vjf4-gxv4

Caddy forward_auth copy_headers Does Not Strip Client-Supplied Headers, Allowing Identity Injection and Privilege Escalation

CVSS 8.1 HighEPSS 0.0029 · 21st percentile

Published by the GitHub Advisory Database at 6 Mar 2026, 23:38 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/caddyserver/caddy/v2/modules/caddyhttp/reverseproxyGo>=2.10.0, <2.11.22.11.2
Identifiers
GHSA-7r4p-vjf4-gxv4 · CVE-2026-30851 · GO-2026-4639
Weakness (CWE)
CWE-287 · CWE-345
Tags
Published
6 Mar 2026
Updated
23 Mar 2026

Machine-written summary

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

Caddy's reverseproxy module (Go github.com/caddyserver/caddy/v2/modules/caddyhttp/reverseproxy) versions 2.10.0 up to but not including 2.11.2 are affected. When forward_auth uses copy_headers and the auth service returns 200 without one of those headers, a client-supplied header with the same name is not removed and reaches the backend. An attacker holding any valid auth token can therefore forge identity headers such as X-User-Id and gain privileges. Upgrade to version 2.11.2, which fixes the issue.

Written 7 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

ScoreRatingCVSSVectorSource
8.1 High 3.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0029, the 21st percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 15:09 UTC First seen by agentprime
  2. 31 Oct 2026, 15:09 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.