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CVE-2026-20349

Cisco Secure Firewall Adaptive Security Appliance (ASA) And Secure Firewall Threat Defense (FTD)•HIGH · CVSS 8.6• In the wild In CISA KEV

What is CVE-2026-20349?

A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

CVSS8.6 NVD 3.1

SeverityHIGH

Exploitation In the wild In CISA KEV

EPSS1% · P63

Triage statusActive Exploit

ActionPatch immediately

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CWECWE-244

NVD published2026-08-11

NVD last modified2026-10-26

Timeline

2026-08-11Published to the U.S. National Vulnerability Database (NVD)
2026-08-11Added to the CISA Known Exploited Vulnerabilities (KEV) catalog
2026-08-13First covered in a defend.network daily briefing
2026-08-14CISA federal remediation deadline (BOD 22-01)
2026-10-26NVD record last updated

CISA Known Exploited Vulnerability

Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability

Added to KEV2026-08-11

Federal patch deadline2026-08-14

Known ransomware useUnknown

Affected product

Cisco Secure Firewall Adaptive Security Appliance (ASA) And Secure Firewall Threat Defense (FTD)

NVD also lists CPE entries for: Cisco Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense

Remediation Steps

Apply the vendor security update for Cisco Adaptive Security Appliance Software as a priority.
Restrict network exposure of the affected service to trusted sources until patched.
Review logs and detections for indicators of exploitation.
Confirm fixed versions against the official vendor advisory before deploying.

References

Referenced in our briefings & reports

Vulnerability Priority Report – Week 1 of September 2026 (September 7 – 13)
Vulnerability Priority Report – Week 5 of August 2026 (August 31 – September 6)
Vulnerability Priority Report – Week 4 of August 2026 (August 24 – 30)
Vulnerability Priority Report – Week 3 of August 2026 (August 17 – 23)
Vulnerability Priority Report – Week 2 of August 2026 (August 10 – 16)
SharePoint auth bypass exploited; 737 Chrome VPN extensions abused; Microsoft patches 398 flaws (2026-08-14)
Lazarus Windows zero-day, Adobe CVSS 10.0 patches, 737 malicious Chrome VPN extensions (2026-08-13)

Related vulnerabilities

CVE-2026-76418 – Cisco Secure Firewall ASA Software And Cisco Secure FTD Software (same product)
CVE-2026-76519 – Cisco Secure Email Gateway (same vendor)
CVE-2026-76504 – Cisco Catalyst SD-WAN Manager (same vendor)
CVE-2026-76460 – Cisco Identity Services Engine (same vendor)
CVE-2026-76461 – Cisco Secure Email Gateway (same vendor)
CVE-2026-20316 – Cisco Secure Firewall Management Center (FMC) (same vendor)

Cisco: 102 known exploited vulnerabilities (CISA KEV) →

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🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.