CVE-2025-23388: Rancher allows an unauthenticated stack overflow in /v3-public/authproviders API

An unauthenticated stack overflow crash, leading to a denial of service (DoS), was identified in Rancher’s /v3-public/authproviders public API endpoint. A malicious user could submit data to the API which would cause the Rancher server to crash, but no malicious or incorrect data would actually be written in the API. The downstream clusters, i.e., the clusters managed by Rancher, are not affected by this issue.

This vulnerability affects those using external authentication providers as well as Rancher’s local authentication.