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Advisory record · GHSA-j6qf-3m9c-vwj3

chi: Client IP spoofing in ClientIPFromXFF via X-Forwarded-For

CVSS 6.3 MediumEPSS 0.0013 · 2nd percentile

Published by the GitHub Advisory Database at 23 Oct 2026, 20:56 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/go-chi/chi/v5Go<5.4.05.4.0
Identifiers
GHSA-j6qf-3m9c-vwj3 · CVE-2026-114437
Weakness (CWE)
CWE-345 · CWE-348
Tags
Published
23 Oct 2026
Updated
23 Oct 2026

Machine-written summary

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

The chi package github.com/go-chi/chi/v5 before 5.4.0 is vulnerable in its ClientIPFromXFF middleware, which does not verify that the direct TCP peer belongs to a configured trusted proxy CIDR before trusting X-Forwarded-For entries. An unauthenticated attacker who can reach the server directly can send a forged X-Forwarded-For header to make the client IP appear as an allowlisted address, which can bypass IP-based access controls. Upgrade to version 5.4.0 or later. The source gives no workaround.

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

ScoreRatingCVSSVectorSource
6.3 Medium 4.0 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N CNA (tenable)
  • CISA KEV Not listed.
  • EPSS 0.0013, the 2nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:11 UTC First seen by agentprime
  2. 31 Oct 2026, 14:11 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.