CVE-2026-20349 - Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability (known exploited)
Added to CISA KEV on 2026-08-11. 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.
CRITICAL
CISA KEV
ACTIVELY EXPLOITED
Severity & confidence
Source severitycritical
Platform severitycritical
Confidencehigh
Exploitationactively exploited
CVSS-
Affected
Vendorscisco
ProductsSecure Firewall Adaptive Security Appliance (ASA)Secure Firewall Threat Defense (FTD)
Sectorsdefence
Reporting sources (2)
CISA - Known Exploited Vulnerabilities
CISA - Cybersecurity Advisories
๐ฏ Why should I care?
- On the CISA Known Exploited Vulnerabilities list.
- Credible sources report active exploitation in the wild.
Timeline & provenance
Published2026-08-11T00:00:00
Last updated2026-10-21T04:58:06
Ingested2026-08-21T04:39:09
FreshnessNEAR-REAL-TIME
Threat typeexploitation
Recommended action
Apply the vendor-supplied patch immediately. Review vendor and CISA guidance for detection and mitigation.
Next steps
- Identify affected systems in your environment.
- Apply the vendor patch or mitigation guidance.
- Review logs for indicators described in the advisory.
- Follow the affected vendor/product to track updates.
Confidence explanation
Reported by a government or cert-grade source (CISA, NCSC, NVD, ENISA, MSRC).
Source type: gov ยท Original: CISA - Known Exploited Vulnerabilities
