Cisco Secure Firewall Adaptive Security Appliance (ASA) Software vulnerability

What happened

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Secure Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense Software and Cisco Secure Firewall Management Center Software engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20335 are related to incorrect calculation issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-682.

Affected versions

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software: 9.16.1; 9.16.1.28; 9.16.2; 9.16.2.3; 9.16.2.7; 9.16.2.11; 9.16.2.13; 9.16.2.14; 9.16.3.3; 9.16.3; 9.16.3.14; 9.16.3.15; 9.18.1.3; 9.18.2; 9.16.3.19; 9.16.3.23; 9.18.2.5; 9.16.4; 9.18.2.7; 9.16.4.9; 9.18.2.8; 9.16.4.14; 9.18.3; 9.16.4.18; 9.18.3.39; 9.16.4.19; 9.18.3.46; 9.16.4.27; 9.18.3.53; 9.18.3.55; 9.16.4.38; 9.16.4.39; 9.18.3.56; 9.20.1; 9.16.4.42; 9.18.4; 9.20.1.5; 9.18.4.5; 9.16.4.48; 9.18.4.8; 9.20.2; 9.16.4.55; 9.18.4.22; 9.20.2.10; 9.16.4.57; 9.18.4.24; 9.20.2.21; 9.16.4.61; 9.18.4.29; 9.20.2.22; 9.16.4.62; 9.18.4.34; 9.20.3; 9.16.4.67; 9.16.4.70; 9.18.4.40; 9.23.1; 9.22.1.1; 9.16.4.71; 9.20.3.4; 9.18.4.47; 9.20.3.7; 9.16.4.76; 9.20.3.9; 9.18.4.50; 9.22.1.3; 9.20.3.10; 9.22.1.2; 9.18.4.52; 9.20.3.13; 9.22.1.6; 9.18.4.53; 9.16.4.82; 9.22.2; 9.20.3.16; 9.19.1.42; 9.18.4.57; 9.16.4.84; 9.23.1.3; 9.20.3.20; 9.22.2.4; 9.23.1.7; 9.20.4; 9.22.2.9; 9.23.1.13; 9.20.4.7; 9.22.2.13; 9.18.4.66; 9.20.4.10; 9.23.1.19; 9.16.4.85; 9.22.2.14; 9.18.4.67; 9.24.1; 9.18.4.68; 9.23.1.22; 9.20.4.14; 9.22.2.20; 9.18.4.71; 9.20.4.19; 9.23.1.26; 9.16.4.89; 9.22.2.32; 9.18.4.76; 9.22.3; 9.24.1.5; 9.20.4.22; 9.24.1.9; 9.20.4.28; 9.22.3.5; 9.16.4.92; 9.18.4.135; 9.23.1.195; 9.20.4.30; 9.24.1.155; 9.23.1.32; 9.24.1.11; 9.20.4.34; 9.18.4.82; 9.24.10; 9.23.1.211; 9.20.4.235; 9.24.1.221; 9.22.3.191; 7.0.0; 7.0.0.1; 7.0.1; 7.0.1.1; 7.0.2; 7.2.0; 7.0.2.1; 7.0.3; 7.2.0.1; 7.0.4; 7.2.1; 7.0.5; 7.3.0; 7.2.2; 7.3.1; 7.2.3; 7.2.3.1; 7.2.4; 7.0.6; 7.2.4.1; 7.2.5; 7.3.1.1; 7.4.0; 7.0.6.1; 7.2.5.1; 7.4.1; 7.2.6; 7.4.1.1; 7.0.6.2; 7.2.7; 7.2.5.2; 7.3.1.2; 7.2.8; 7.6.0; 7.4.2; 7.2.8.1; 7.0.6.3; 7.4.2.1; 7.2.9; 7.0.7; 7.7.0; 7.4.2.2; 7.2.10; 7.6.1; 7.4.2.3; 7.0.8; 7.6.2; 7.7.10; 7.2.10.1; 7.0.8.1; 7.6.2.1; 7.2.10.2; 7.7.10.1; 7.4.2.4; 7.4.3; 7.6.3; 7.7.11; 7.6.4; 10.0.0; 7.4.4; 7.4.5; 7.0.9; 7.2.11; 7.7.12; 7.6.5; 7.4.6; 10.0.1; 7.4.7 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.