A flaw in Samba’s internal DNS server allows unauthenticated TKEY registration requests to be cached before rejection; a remote attacker can flood the server with many such requests using arbitrary names, causing cache exhaustion that evicts legitimate TKEY entries. The result is that legitimate TSIG authentication for signed DNS queries fails, leading to a denial of service for DNS signing and related services.

The vulnerability affects Samba running on Red Enterprise Linux 6 through 10 and on Red OpenShift Container Platform 4. No specific Samba version is listed; any installation of Samba on these platforms that supports DNS signing is potentially vulnerable.

The CVSS score of 5.3 indicates a moderate severity, and the EPSS score of 1% suggests a low but non‑zero exploitation potential. The lack of a KEV listing combined with the remote unauthenticated nature of the attack indicates that the vulnerability is realistic but unlikely to be widely exploited. An attacker would need only network access to the machine’s DNS service to trigger the denial of service by sending a high volume of TKEY requests.