# 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 Advisory record · `GHSA-c8w2-fgvx-vhv4` - **Identifiers:** `GHSA-c8w2-fgvx-vhv4` · `CVE-2026-61682` · `GO-2026-6517` - **State:** Confirmed - **Severity:** CVSS 9.9 Critical - **Critical:** Yes: CVSS 9+ - **Weakness (CWE):** [CWE-290](https://cwe.mitre.org/data/definitions/290.html) · [CWE-302](https://cwe.mitre.org/data/definitions/302.html) · [CWE-348](https://cwe.mitre.org/data/definitions/348.html) - **Tags:** [Authentication bypass](https://agentprime.io/advisories/tag/auth-bypass.md) · [CWE-302](https://agentprime.io/advisories/tag/cwe-302.md) · [CWE-348](https://agentprime.io/advisories/tag/cwe-348.md) - **Published:** 18 Sept 2026 - **Updated:** 28 Sept 2026 - **Reviewed by a person:** No 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. ## Critical Critical, because: - CVSS score 9.9: 9.0 or more. How we decide what’s critical: ## Affected packages - `github.com/kcp-dev/kcp` (Go): affected `<0.31.4 || >=0.32.0, <0.32.2`; fixed in `0.31.4`, `0.32.2` ## 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 - 9.9 Critical, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`, from 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 - 31 Oct 2026, 14:12 UTC: First seen by agentprime - 31 Oct 2026, 14:12 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-c8w2-fgvx-vhv4) ## Sources - [GitHub Advisory Database: GHSA-c8w2-fgvx-vhv4](https://github.com/advisories/GHSA-c8w2-fgvx-vhv4) - [OSV: GHSA-c8w2-fgvx-vhv4](https://osv.dev/vulnerability/GHSA-c8w2-fgvx-vhv4) - - - - - 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. ## Check whether this affects you A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet. - With the agentprime MCP server (), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .