Risk Letters

Exploited vulnerability

CVE-2026-20349

TLP:CLEAR

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.

Facts

  • Vendor: Cisco
  • Product: Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD)
  • CVSS: 8.6
  • EPSS (probability of exploitation within 30 days): 1 %
  • On CISA's Known Exploited Vulnerabilities list since: 11 August 2026
  • First known exploitation: 11 August 2026
  • CISA's deadline for US federal agencies: 14 August 2026
  • Weakness: CWE-244
  • First seen by Risk Letters: 25 August 2026

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Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD