Vulnerability in github.com/kcp-dev/kcp (CVE-2026-61682)
Summary
Vulnerability in github.com/kcp-dev/kcp (CVE-2026-61682). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 0.31.4 or later.
Original description
The description as published by the source.
Summary
The kcp front-proxy fails to strip client-supplied identity headers before forwarding requests to shards. Any authenticated tenant can inject their own X-Remote-Group and X-Remote-Extra-* headers, which the shard trusts as a verified identity assertion — allowing a low-privilege user to escalate to cluster administrator (system:masters) and read, write, or delete resources in any workspace on the shard. This is a complete multi-tenant isolation and authorization bypass.
Impact
In a sharded kcp deployment, external clients reach shards through the front-proxy, which authenticates the client and then forwards the resulting identity to the shard using Kubernetes request-header authentication (X-Remote-User / X-Remote-Group / X-Remote-Extra-*). The shard trusts these headers because they arrive over the front-proxy's mutually-authenticated connection.
Because the front-proxy appended its identity headers instead of replacing them — and never removed any copies the client sent — an authenticated attacker could smuggle forged identity headers through to the shard. With this, an attacker holding any ordinary credential (client certificate, OIDC token, or service-account token) and no special privileges could:
- assert
X-Remote-Group: system:mastersand act as cluster super-user, bypassing the entire kcp authorizer chain in every workspace on the shard; - forge
authorization.kcp.io/warrantto assume an arbitrary user/group identity via kcp's delegat…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-61682 has been found in github.com/kcp-dev/kcp.
Successful exploitation can lead to full system takeover. CVSS score: 9.9/10.
What to do: upgrade github.com/kcp-dev/kcp to 0.31.4 or later.
If unsure, ask your IT team or search "github.com/kcp-dev/kcp CVE-2026-61682" on the vendor's site.
CVE-2026-61682 (github.com/kcp-dev/kcp) — CWE-290 / CVSS v3 9.9
Attack vector: remote (network-reachable) / no user interaction
Patched: 0.31.4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-290) exists in github.com/kcp-dev/kcp.
Check the vendor advisory for the affected versions of github.com/kcp-dev/kcp.
Severity: Critical (CVSS 9.9/10). Successful exploitation can lead to full system takeover.
Update to 0.31.4.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/kcp-dev/kcp' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/kcp-dev/kcp' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/kcp-dev/kcpを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade github.com/kcp-dev/kcp to 0.31.4ステージング環境で 0.31.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- web github.com
- web security-advisories@github.com
- web github.com
- web github.com
- web github.com
- web github.com