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Advisory record · GHSA-c8w2-fgvx-vhv4

kcp front-proxy does not strip inbound X-Remote-* identity headers, allowing any authenticated client to inject groups/warrants and impersonate system:masters in any workspace

CVSS 9.9 CriticalCriticalEPSS 0.0038 · 32nd percentile

Critical, because:

  • CVSS score 9.9: 9.0 or more.

How we decide what’s critical

Published by the GitHub Advisory Database at 18 Sept 2026, 17:15 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/kcp-dev/kcpGo<0.31.4 || >=0.32.0, <0.32.20.31.4, 0.32.2
Identifiers
GHSA-c8w2-fgvx-vhv4 · CVE-2026-61682 · GO-2026-6517
Weakness (CWE)
CWE-290 · CWE-302 · CWE-348
Tags
Published
18 Sept 2026
Updated
28 Sept 2026

Machine-written summary

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

The kcp front-proxy in github.com/kcp-dev/kcp versions before 0.31.4, and from 0.32.0 before 0.32.2, does not strip client-supplied X-Remote-* identity headers before forwarding requests to shards. An authenticated client can therefore inject group and extra identity values that shards trust, which can lead to system:masters access and cross-workspace read, write, and delete of resources. Upgrade to 0.31.4 or 0.32.2. Until then, an external proxy that removes X-Remote-* headers from inbound requests can reduce exposure.

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
9.9 Critical 3.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0038, the 32nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:12 UTC First seen by agentprime
  2. 31 Oct 2026, 14:12 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.