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GHSA-c7xh-gjv4-4jgv
No affected components available
Impact
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.
Patches
The problem has been patched in #3206 and is available in kcp 0.26.1 and higher.
Workarounds
- Not assigning the
cluster-adminrole (or any other role granting blanket impersonation permissions) to users. - A reverse proxy between users and kcp to check for the
Impersonate-Groupheader and reject requests that impersonate global administrative groups.
References
See the pull request (#3206).
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
Probability that this vulnerability will be exploited in the wild within the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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