CVE-2026-61682
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.
What this means for your business
- An attacker can use it remotely, over a network, with an ordinary user login, and without anyone at your company clicking anything.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 9.9 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H- Weakness
- CWE-290
- Assigned by
- security-advisories@github.com
Dates
- Published
- 2026-09-18
- Last modified
- 2026-09-24
- Sources
- NVD
References
- 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
- https://github.com/kcp-dev/kcp/security/advisories/GHSA-c8w2-fgvx-vhv4