--- id: CVE-2026-20349 title: >- 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 th… summary: >- 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 th… severity: high cvss: 8.6 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H' cwe: - CWE-244 vendor: cisco product: adaptive_security_appliance_software affected: - adaptive_security_appliance_software = 9.16.1 - adaptive_security_appliance_software = 9.16.1.28 - adaptive_security_appliance_software = 9.16.2 - adaptive_security_appliance_software = 9.16.2.3 - adaptive_security_appliance_software = 9.16.2.7 - adaptive_security_appliance_software = 9.16.2.11 - adaptive_security_appliance_software = 9.16.2.13 - adaptive_security_appliance_software = 9.16.2.14 - adaptive_security_appliance_software = 9.16.3 - adaptive_security_appliance_software = 9.16.3.3 - adaptive_security_appliance_software = 9.16.3.14 - adaptive_security_appliance_software = 9.16.3.15 - adaptive_security_appliance_software = 9.16.3.19 - adaptive_security_appliance_software = 9.16.3.23 - adaptive_security_appliance_software = 9.16.4 - adaptive_security_appliance_software = 9.16.4.9 - adaptive_security_appliance_software = 9.16.4.14 - adaptive_security_appliance_software = 9.16.4.19 - adaptive_security_appliance_software = 9.16.4.27 - adaptive_security_appliance_software = 9.16.4.38 - adaptive_security_appliance_software = 9.16.4.39 - adaptive_security_appliance_software = 9.16.4.42 - adaptive_security_appliance_software = 9.16.4.48 - adaptive_security_appliance_software = 9.16.4.55 - adaptive_security_appliance_software = 9.16.4.57 - adaptive_security_appliance_software = 9.16.4.61 - adaptive_security_appliance_software = 9.16.4.62 - adaptive_security_appliance_software = 9.16.4.67 - adaptive_security_appliance_software = 9.16.4.70 - adaptive_security_appliance_software = 9.16.4.71 - adaptive_security_appliance_software = 9.16.4.76 - adaptive_security_appliance_software = 9.16.4.82 - adaptive_security_appliance_software = 9.16.4.84 - adaptive_security_appliance_software = 9.16.4.85 - adaptive_security_appliance_software = 9.16.4.89 - adaptive_security_appliance_software = 9.16.4.92 - adaptive_security_appliance_software = 9.18.1 - adaptive_security_appliance_software = 9.18.1.3 - adaptive_security_appliance_software = 9.18.2 - adaptive_security_appliance_software = 9.18.2.5 - adaptive_security_appliance_software = 9.18.2.7 - adaptive_security_appliance_software = 9.18.2.8 - adaptive_security_appliance_software = 9.18.3 - adaptive_security_appliance_software = 9.18.3.39 - adaptive_security_appliance_software = 9.18.3.46 - adaptive_security_appliance_software = 9.18.3.53 - adaptive_security_appliance_software = 9.18.3.55 - adaptive_security_appliance_software = 9.18.3.56 - adaptive_security_appliance_software = 9.18.4 - adaptive_security_appliance_software = 9.18.4.5 - adaptive_security_appliance_software = 9.18.4.8 - adaptive_security_appliance_software = 9.18.4.22 - adaptive_security_appliance_software = 9.18.4.24 - adaptive_security_appliance_software = 9.18.4.29 - adaptive_security_appliance_software = 9.18.4.34 - adaptive_security_appliance_software = 9.18.4.40 - adaptive_security_appliance_software = 9.18.4.47 - adaptive_security_appliance_software = 9.18.4.50 - adaptive_security_appliance_software = 9.18.4.52 - adaptive_security_appliance_software = 9.18.4.53 - adaptive_security_appliance_software = 9.18.4.57 - adaptive_security_appliance_software = 9.18.4.66 - adaptive_security_appliance_software = 9.18.4.67 - adaptive_security_appliance_software = 9.18.4.68 - adaptive_security_appliance_software = 9.18.4.71 - adaptive_security_appliance_software = 9.18.4.76 - adaptive_security_appliance_software = 9.18.4.82 - adaptive_security_appliance_software = 9.18.4.90 - adaptive_security_appliance_software = 9.18.4.135 - adaptive_security_appliance_software = 9.19.1 - adaptive_security_appliance_software = 9.19.1.5 - adaptive_security_appliance_software = 9.19.1.9 - adaptive_security_appliance_software = 9.19.1.12 - adaptive_security_appliance_software = 9.19.1.18 - adaptive_security_appliance_software = 9.19.1.22 - adaptive_security_appliance_software = 9.19.1.24 - adaptive_security_appliance_software = 9.19.1.27 - adaptive_security_appliance_software = 9.19.1.28 - adaptive_security_appliance_software = 9.19.1.31 - adaptive_security_appliance_software = 9.19.1.37 - adaptive_security_appliance_software = 9.19.1.38 - adaptive_security_appliance_software = 9.19.1.42 - adaptive_security_appliance_software = 9.20.1 - adaptive_security_appliance_software = 9.20.1.5 - adaptive_security_appliance_software = 9.20.2 - adaptive_security_appliance_software = 9.20.2.10 - adaptive_security_appliance_software = 9.20.2.21 - adaptive_security_appliance_software = 9.20.2.22 - adaptive_security_appliance_software = 9.20.3 - adaptive_security_appliance_software = 9.20.3.4 - adaptive_security_appliance_software = 9.20.3.7 - adaptive_security_appliance_software = 9.20.3.9 - adaptive_security_appliance_software = 9.20.3.10 - adaptive_security_appliance_software = 9.20.3.13 - adaptive_security_appliance_software = 9.20.3.16 - adaptive_security_appliance_software = 9.20.3.20 - adaptive_security_appliance_software = 9.20.4 - adaptive_security_appliance_software = 9.20.4.7 - adaptive_security_appliance_software = 9.20.4.10 - adaptive_security_appliance_software = 9.20.4.14 published: '2026-08-11' updated: '2026-09-16' sourceUpdated: '2026-09-16T21:17:12.103' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-20349' references: - url: >- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-dzv4mQFF label: psirt@cisco.com - url: >- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20349 label: 134c704f-9b21-4f2e-91b3-4a467353bcc0 - url: 'https://software.cisco.com' tags: - nvd - kev - in-the-wild - cve.org - exploit-available - csaf - vendor-advisory - cisco epss: 0.02213 epssPercentile: 0.81639 kev: true kevDateAdded: '2026-08-11' kevDueDate: '2026-08-14' kevRansomware: false exploited: true zeroDay: true exploitAvailable: true ssvc: exploitation: active automatable: 'yes' technicalImpact: partial timestamp: '2026-08-11T00:00:00+00:00' ingestedAt: '2026-09-11T03:25:42.953Z' --- ## Overview 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. ## Affected - `adaptive_security_appliance_software = 9.16.1` - `adaptive_security_appliance_software = 9.16.1.28` - `adaptive_security_appliance_software = 9.16.2` - `adaptive_security_appliance_software = 9.16.2.3` - `adaptive_security_appliance_software = 9.16.2.7` - `adaptive_security_appliance_software = 9.16.2.11` - `adaptive_security_appliance_software = 9.16.2.13` - `adaptive_security_appliance_software = 9.16.2.14` - `adaptive_security_appliance_software = 9.16.3` - `adaptive_security_appliance_software = 9.16.3.3` - `adaptive_security_appliance_software = 9.16.3.14` - `adaptive_security_appliance_software = 9.16.3.15` - `adaptive_security_appliance_software = 9.16.3.19` - `adaptive_security_appliance_software = 9.16.3.23` - `adaptive_security_appliance_software = 9.16.4` - `adaptive_security_appliance_software = 9.16.4.9` - `adaptive_security_appliance_software = 9.16.4.14` - `adaptive_security_appliance_software = 9.16.4.19` - `adaptive_security_appliance_software = 9.16.4.27` - `adaptive_security_appliance_software = 9.16.4.38` - `adaptive_security_appliance_software = 9.16.4.39` - `adaptive_security_appliance_software = 9.16.4.42` - `adaptive_security_appliance_software = 9.16.4.48` - `adaptive_security_appliance_software = 9.16.4.55` - `adaptive_security_appliance_software = 9.16.4.57` - `adaptive_security_appliance_software = 9.16.4.61` - `adaptive_security_appliance_software = 9.16.4.62` - `adaptive_security_appliance_software = 9.16.4.67` - `adaptive_security_appliance_software = 9.16.4.70` - `adaptive_security_appliance_software = 9.16.4.71` - `adaptive_security_appliance_software = 9.16.4.76` - `adaptive_security_appliance_software = 9.16.4.82` - `adaptive_security_appliance_software = 9.16.4.84` - `adaptive_security_appliance_software = 9.16.4.85` - `adaptive_security_appliance_software = 9.16.4.89` - `adaptive_security_appliance_software = 9.16.4.92` - `adaptive_security_appliance_software = 9.18.1` - `adaptive_security_appliance_software = 9.18.1.3` - `adaptive_security_appliance_software = 9.18.2` - `adaptive_security_appliance_software = 9.18.2.5` - `adaptive_security_appliance_software = 9.18.2.7` - `adaptive_security_appliance_software = 9.18.2.8` - `adaptive_security_appliance_software = 9.18.3` - `adaptive_security_appliance_software = 9.18.3.39` - `adaptive_security_appliance_software = 9.18.3.46` - `adaptive_security_appliance_software = 9.18.3.53` - `adaptive_security_appliance_software = 9.18.3.55` - `adaptive_security_appliance_software = 9.18.3.56` - `adaptive_security_appliance_software = 9.18.4` - `adaptive_security_appliance_software = 9.18.4.5` - `adaptive_security_appliance_software = 9.18.4.8` - `adaptive_security_appliance_software = 9.18.4.22` - `adaptive_security_appliance_software = 9.18.4.24` - `adaptive_security_appliance_software = 9.18.4.29` - `adaptive_security_appliance_software = 9.18.4.34` - `adaptive_security_appliance_software = 9.18.4.40` - `adaptive_security_appliance_software = 9.18.4.47` - `adaptive_security_appliance_software = 9.18.4.50` - `adaptive_security_appliance_software = 9.18.4.52` - `adaptive_security_appliance_software = 9.18.4.53` - `adaptive_security_appliance_software = 9.18.4.57` - `adaptive_security_appliance_software = 9.18.4.66` - `adaptive_security_appliance_software = 9.18.4.67` - `adaptive_security_appliance_software = 9.18.4.68` - `adaptive_security_appliance_software = 9.18.4.71` - `adaptive_security_appliance_software = 9.18.4.76` - `adaptive_security_appliance_software = 9.18.4.82` - `adaptive_security_appliance_software = 9.18.4.90` - `adaptive_security_appliance_software = 9.18.4.135` - `adaptive_security_appliance_software = 9.19.1` - `adaptive_security_appliance_software = 9.19.1.5` - `adaptive_security_appliance_software = 9.19.1.9` - `adaptive_security_appliance_software = 9.19.1.12` - `adaptive_security_appliance_software = 9.19.1.18` - `adaptive_security_appliance_software = 9.19.1.22` - `adaptive_security_appliance_software = 9.19.1.24` - `adaptive_security_appliance_software = 9.19.1.27` - `adaptive_security_appliance_software = 9.19.1.28` - `adaptive_security_appliance_software = 9.19.1.31` - `adaptive_security_appliance_software = 9.19.1.37` - `adaptive_security_appliance_software = 9.19.1.38` - `adaptive_security_appliance_software = 9.19.1.42` - `adaptive_security_appliance_software = 9.20.1` - `adaptive_security_appliance_software = 9.20.1.5` - `adaptive_security_appliance_software = 9.20.2` - `adaptive_security_appliance_software = 9.20.2.10` - `adaptive_security_appliance_software = 9.20.2.21` - `adaptive_security_appliance_software = 9.20.2.22` - `adaptive_security_appliance_software = 9.20.3` - `adaptive_security_appliance_software = 9.20.3.4` - `adaptive_security_appliance_software = 9.20.3.7` - `adaptive_security_appliance_software = 9.20.3.9` - `adaptive_security_appliance_software = 9.20.3.10` - `adaptive_security_appliance_software = 9.20.3.13` - `adaptive_security_appliance_software = 9.20.3.16` - `adaptive_security_appliance_software = 9.20.3.20` - `adaptive_security_appliance_software = 9.20.4` - `adaptive_security_appliance_software = 9.20.4.7` - `adaptive_security_appliance_software = 9.20.4.10` - `adaptive_security_appliance_software = 9.20.4.14` ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **cisco-sa-asaftd-vpn-dos-dzv4mQFF** · Cisco · affected: Cisco Firepower 2100 Series, Cisco Firepower 1000 Series, Cisco ASA 5500-X Series Firewalls, Cisco 3000 Series Industrial Security Appliances (ISA), Cisco Firepower 9000 Series, Cisco Firepower 4100 Series, … · updated 2026-09-16 · [advisory](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-dzv4mQFF)