Cisco Secure Firewall ASA Software and Cisco Secure FTD Software Unchecked Return Value to NULL Pointer Dereference Vulnerability

Cisco Secure Firewall ASA Software and Cisco Secure FTD Software contains an unchecked return value to NULL pointer dereference vulnerability that could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.

Why it matters

• This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, which means it has been observed being exploited in the wild.

Affected

• Vendor: Cisco
• Product: Secure Firewall ASA Software and Cisco Secure FTD Software
• Identifier: CVE-2026-76418
• FlawFind severity: high
• Weakness: CWE-690

What to do

• Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
• U.S. federal remediation deadline: 2026-11-01
• Inventory the affected product, prioritise internet-facing instances, and patch or mitigate immediately.
• Audit your own systems for the same weakness class — FlawFind can test your applications and APIs for it and prove what is exploitable.

Notes

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-tunnel-dos-s6mgkb75 ; ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-76418