CVE-2021-3560

Red Hat's Polkit (PolicyKit), the component that enforces authorization policy for privileged D-Bus requests, fails to correctly verify credentials for D-Bus requests: when the calling client drops its connection before the authorization check completes, Polkit treats the request as if it came from a privileged process. A local, unprivileged user can trigger this by initiating a D-Bus call to a system service and terminating the connection at the right moment, making the race straightforward to hit with repeated attempts. A successful exploit bypasses the credential check and escalates the attacker's privileges to root on the affected host. Any Red Hat system shipping the vulnerable Polkit build is affected, and no public proof-of-concept is documented. The flaw is on CISA's Known Exploited Vulnerabilities catalog (added 2023-05-12), which indicates known exploitation in the wild, though ransomware use is unknown.

What to do: Apply updated Polkit packages per Red Hat's advisory instructions on all affected systems, and verify the running Polkit version matches the vendor's fixed release. Because the flaw is CISA KEV-listed with a 22.2% EPSS, prioritize patching on multi-user and internet-exposed hosts; where patching is delayed, restrict local shell access to untrusted users, since the flaw requires local access to trigger.