# CVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability

> CVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability. CVSS 8.6 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2026-20349
Last updated: 2026-09-16T21:17:12Z

- Published: 2026-08-11 17:06 UTC · Updated: 2026-09-16 21:17 UTC · Assigner: cisco
- CVSS: 8.6 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- EPSS: 1.0%, 63th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2026-08-11, federal due date 2026-08-14, ransomware use: Unknown
- CWE: CWE-244

## Description

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.

## CISA required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

## Affected vendors and products

- Cisco: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
- Cisco: Cisco Secure Firewall Threat Defense (FTD) Software

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-20349)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-20349)
- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-dzv4mQFF](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-dzv4mQFF)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-20349 · Markdown: https://rewindex.com/cve/CVE-2026-20349.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-20349 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:15:50.427Z