CVE-2026-20049: cisco adaptive_security_appliance_software Incorrect Calculation of Buffer Size

Vulnerability summary

CVE-2026-20049 is a high (CVSS 7.7) Incorrect Calculation of Buffer Size vulnerability in cisco adaptive_security_appliance_software. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 21.9% of scored vulnerabilities.

Timeline

1. 04-03-2026
   PublishedVulnerability first disclosed.
2. 04-03-2026
   Last modifiedVulnerability information updated.

Description

A vulnerability in the processing of Galois/Counter Mode (GCM)-encrypted Internet Key Exchange version 2 (IKEv2) IPsec traffic of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to the allocation of an insufficiently sized block of memory. An attacker could exploit this vulnerability by sending crafted GCM-encrypted IPsec traffic to an affected device. A successful exploit could allow the attacker to cause an unexpected reload of the device, resulting in a DoS condition. To exploit this vulnerability, the attacker must have valid credentials to establish a VPN connection with the affected device.

• CWE-131Incorrect Calculation of Buffer SizeThe product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.