A buffer overflow vulnerability in OpenAirInterface 5G AUSF allows unauthenticated remote attackers to cause a denial of service by crashing the authentication component.

The vulnerability is a buffer overflow occurring during the processing of UplinkNASTransport messages containing an Authentication Response. An unauthenticated remote attacker can trigger an AUSF crash by sending a NAS PDU with an oversized response, such as 100 bytes, which the system fails to handle correctly.

The exploitation of this vulnerability results in a denial of service for the Authentication Server Function. Because this component is critical for user registration and verification, a successful attack prevents legitimate users from accessing network services, leading to significant operational disruption. Given the CVSS score of 7.5, this is considered a high-severity issue that directly impacts the availability of telecommunications infrastructure.

Immediate Action: Monitor official OpenAirInterface GitLab repositories for the release of a security patch addressing this buffer overflow and apply it immediately upon availability.

Proactive Monitoring: Review access and application logs for abnormal UplinkNASTransport traffic or repeated authentication component crashes that may indicate exploitation attempts.

Compensating Controls: Implement strict input validation or rate limiting at the network edge or via a firewall to block malformed or oversized NAS PDU packets before they reach the AUSF component.

Public Exploit Available: Unknown.

This vulnerability represents a significant risk to the availability of OpenAirInterface 5G deployments due to the ease of triggering a crash without authentication. Administrators must prioritize monitoring the project's issue trackers and repository for an official fix. Until a patch is deployed, network operators should implement traffic filtering to intercept and drop malformed authentication requests that exceed expected size parameters.