A flaw was found in Red Hat Advanced Cluster Security for Kubernetes (RHACS). The Central SAML authentication ACS endpoint does not retain used SAML assertion or response identifiers to prevent replay. An attacker who obtains a valid, unexpired signed SAML response can submit it multiple times and receive distinct Central authentication tokens for the mapped identity.
Until an update is available, restrict network access to the Central SAML ACS endpoint to trusted identity providers and networks, and reduce SAML assertion lifetimes at the identity provider where possible.