CVE entry · CVE-2026-20349
CVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability
Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) contain a heap inspection vulnerability that could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.
- Actively exploited: added to CISA’s KEV catalog on August 11, 2026.
- Use by ransomware: not established so far.
- Remediation deadline for US federal agencies: August 14, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) , including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.
References
- Vendor advisory or reference cited by CISA (sec.cloudapps.cisco.com)
- NVD entry (NIST)
- CISA KEV catalog
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