The flaw is in the handling of OSPF update packets in Cisco Secure Firewall ASA and FTD software. Insufficient input validation can trigger a buffer overflow when a maliciously crafted update packet is received. The overflow causes the device to reload, leading to an interruption of firewall services. This is a classic denial‑of‑service vulnerability that does not grant the attacker any additional privileges.

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software are affected. No specific version range is listed in the advisory, so all released versions prior to the published patch are presumed vulnerable.

The CVSS score of 6.8 marks it as moderately severe. The EPSS score is reported as less than 1% and the vulnerability is not included in CISA’s KEV catalog, indicating a low current exploitation probability. The attack requires the attacker to be on a network adjacent to the host and to send the crafted packet; authentication is not needed unless OSPF authentication is enabled, in which case the attacker must know the shared secret. The simple adjacent, unauthenticated nature of the vector, combined with the requirement for packet crafting, keeps exploitability moderate.