CVE-2026-20335 in Secure Adaptive Security Appliance Software
Summary
by MITRE • 09/16/2026
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.
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Analysis
by VulDB Data Team • 09/17/2026
Cisco has released a software hardening update for its Secure Adaptive Security Appliance, Secure Firewall Threat Defense, and Secure Firewall Management Center platforms following an internal security review aimed at addressing multiple internally discovered vulnerabilities. The specific vulnerability tracked under CVE-2026-20335 stems from incorrect calculation logic within the affected software components. This flaw is categorized under the Common Weakness Enumeration identifier CWE-682, which encompasses Incorrect Calculation errors such as integer overflows or underflows that can lead to unexpected behavior in system operations.
The technical nature of this vulnerability involves a failure in the proper arithmetic processing during specific execution paths within the firewall software stack. When the application performs calculations related to resource allocation, buffer sizing, or state tracking, an incorrect calculation may result in values being misinterpreted by the underlying memory management subsystems. This discrepancy can cause the system to allocate insufficient resources for a given operation or miscalculate critical thresholds that govern packet processing and connection handling. Such logic errors are particularly dangerous because they often occur deep within the core networking functions where precise data integrity is paramount for maintaining secure communications.
From an operational perspective, this vulnerability poses significant risks to network security posture depending on how it can be triggered by an attacker. If exploitable through crafted input or specific traffic patterns, incorrect calculation flaws typically lead to denial of service conditions due to resource exhaustion or application crashes. In more severe scenarios involving memory corruption resulting from the miscalculation, there is a potential risk for remote code execution, allowing unauthorized actors to gain control over the affected firewall devices. This would effectively bypass perimeter defenses and expose internal network assets to further compromise. The impact extends beyond individual device availability as compromised firewalls can be used to pivot laterally within an enterprise environment or exfiltrate sensitive data without detection.
Mitigation strategies primarily involve applying the provided software hardening release immediately to all affected Cisco Secure Adaptive Security Appliance, Secure Firewall Threat Defense, and Secure Firewall Management Center installations. Administrators should verify their current firmware versions against the advisory details and schedule maintenance windows for patch deployment during low-traffic periods to minimize operational disruption. In addition to updating software, organizations should ensure that network segmentation policies are strictly enforced so that even if a firewall is compromised, lateral movement remains restricted. Continuous monitoring of system logs for anomalous behavior indicative of exploitation attempts, such as unusual spikes in CPU usage or unexpected connection drops, can help detect potential abuse before significant damage occurs. Adhering to these remediation steps aligns with industry best practices outlined by the MITRE ATT&CK framework regarding patch management and defense-in-depth strategies to maintain resilient security infrastructure against evolving threats.