GHSA-C7XH-GJV4-4JGV

kcp's impersonation allows access to global administrative groups

Workarounds

• Not assigning the cluster-admin role (or any other role granting blanket impersonation permissions) to users.
• A reverse proxy between users and kcp to check for the Impersonate-Group header and reject requests that impersonate global administrative groups.

References

See the pull request (#3206).

Impersonation is a feature of the Kubernetes API, allowing to override user information. As downstream project, kcp inherits this feature. As per the linked documentation a specific level of privilege (usually assigned to cluster admins) is required for impersonation.

The vulnerability in kcp affects kcp installations in which users are granted the cluster-admin ClusterRole (or comparably high permission levels that grant impersonation access; the verb in question is impersonate) within their respective workspaces. As kcp builds around self-service confined within workspaces, most installations would likely grant such workspace access to their users. Such users can impersonate special global administrative groups, which circumvent parts of the authorizer chains, e.g. maximal permission policies.

GHSA-C7XH-GJV4-4JGV has a CVSS score of 6.4 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.26.1); upgrading removes the vulnerable code path.

Kodem intelligence

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The problem has been patched in #3206 and is available in kcp 0.26.1 and higher.

1. What is GHSA-C7XH-GJV4-4JGV? GHSA-C7XH-GJV4-4JGV is a medium-severity security vulnerability in github.com/kcp-dev/kcp (go), affecting versions <= 0.26.0. It is fixed in 0.26.1.
2. How severe is GHSA-C7XH-GJV4-4JGV? GHSA-C7XH-GJV4-4JGV has a CVSS score of 6.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/kcp-dev/kcp are affected by GHSA-C7XH-GJV4-4JGV? github.com/kcp-dev/kcp (go) versions <= 0.26.0 is affected.
4. Is there a fix for GHSA-C7XH-GJV4-4JGV? Yes. GHSA-C7XH-GJV4-4JGV is fixed in 0.26.1. Upgrade to this version or later.
5. Is GHSA-C7XH-GJV4-4JGV exploitable, and should I be worried? Whether GHSA-C7XH-GJV4-4JGV is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-C7XH-GJV4-4JGV is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-C7XH-GJV4-4JGV? Upgrade github.com/kcp-dev/kcp to 0.26.1 or later.

Other vulnerabilities in github.com/kcp-dev/kcp