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Known exploited vulnerability

CVE-2026-20349

highCVSS 3.1 8.6In CISA KEVEPSS 1.0%Published · Cisco

The short answer

CVE-2026-20349 affects Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and is rated high (CVSS 8.6). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-11: attackers are using it, so patch it first.

What it is

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.

Weakness: CWE-244.

Severity

8.6 high

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

Exploited (CISA KEV)

Yes, since Aug 11, 2026

Federal due date Aug 14, 2026

EPSS, next 30 days

1.0%

Higher than 63% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality impact
None
Integrity impact
None
Availability impact
High

What CISA says to do

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…

Affected products

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-20349 being exploited?

Yes. CISA added CVE-2026-20349 to its Known Exploited Vulnerabilities catalog on 2026-08-11, with a federal remediation due date of 2026-08-14.

How do I fix CVE-2026-20349?

CISA's 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…

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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