CVE-2026-61682
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
- State
- Published
- Severity
- 9.9 Critical
- Published
- Sep 18, 2026
- Updated
- Sep 21, 2026
- Reserved
- Jul 10, 2026
Description
kcp is a Kubernetes-like control plane for form-factors and use-cases beyond Kubernetes and container workloads. Prior to 0.31.4 and 0.32.2, the kcp front-proxy does not remove inbound X-Remote-User, X-Remote-Group, or X-Remote-Extra-* identity headers before forwarding requests to shards. Any authenticated tenant can inject X-Remote-Group: system:masters, authorization.kcp.io/warrant, authentication.kcp.io/scopes, or a group used for per-workspace required-group gating, and the shard trusts these values as authenticated identity assertions. This allows cross-workspace impersonation, authorization bypass, and arbitrary reading, writing, or deletion of resources, secrets, RBAC data, APIExports, APIBindings, and LogicalClusters. This issue is fixed in versions 0.31.4 and 0.32.2.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.9 Critical | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
kcpkcp-dev |
|
References
- https://github.com/kcp-dev/kcp/security/advisories/GHSA-c8w2-fgvx-vhv4
- https://github.com/kcp-dev/kcp/commit/7437cdcfec8f927d1a9bf1b2dd1e075d038e27ca
- https://github.com/kcp-dev/kcp/commit/f913ee890fb2fd9fa78e50c43474b078bfb6aeff
- https://github.com/kcp-dev/kcp/releases/tag/v0.31.4
- https://github.com/kcp-dev/kcp/releases/tag/v0.32.2
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