Buffer overflow in Cisco Adaptive Security Appliance Software

CVE-2026-20023

A vulnerability in the OSPF protocol of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, adjacent attacker to corrupt memory on an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to memory corruption when parsing OSPF protocol packets. An attacker could exploit this vulnerability by sending crafted OSPF packets to an affected device. A successful exploit could allow the attacker to cause memory corruption causing the affected device to reboot, resulting in a DoS condition.

Vulnerability class: Buffer Overflow

EPSS: 0.002 (4.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-20023?
CVE-2026-20023 is a medium-severity vulnerability in Cisco Adaptive Security Appliance Software, classified under Out-of-bounds Write. CVSS score: 6.1/10. Published 2026-03-04.
How severe is CVE-2026-20023?
Medium severity. CVSS v3 base score is 6.1 out of 10.