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IMMUNITYSEC

CVE-2026-20349

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability

8.6
HIGH
CVSS 3.1
EPSS 1.0% · 62nd pctCISA KEV · Exploited in the wild
2026-08-11•Updated 2026-09-16•KEV 2026-08-11
CISA Known Exploited Vulnerabilities

Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV
2026-08-11
Remediation due
2026-08-14

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.

CISA notes
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-dzv4mQFF ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-20349

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.

Severity

CVSS 3.1 · CNA8.6 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
SSVC · CISA-ADP
Exploitationactive
Automatableyes
Technical impactpartial

Affected Products

VendorProductAffected versions
CiscoCisco Secure Firewall Adaptive Security Appliance (ASA) Software
9.16.1
9.16.1.28
9.16.2
9.16.2.3
9.16.2.7
9.16.2.11
9.16.2.13
9.16.2.14
9.16.3.3
9.16.3
9.16.3.14
9.18.1
9.16.3.15
9.18.1.3
9.18.2
9.16.3.19
9.16.3.23
9.18.2.5
9.16.4
9.18.2.7
9.19.1
9.16.4.9
9.18.2.8
9.16.4.14
9.18.3
9.19.1.5
9.16.4.18
9.19.1.9
9.18.3.39
9.16.4.19
9.19.1.12
9.18.3.46
9.16.4.27
9.19.1.18
9.18.3.53
9.18.3.55
9.16.4.38
9.16.4.39
9.18.3.56
9.20.1
9.16.4.42
9.19.1.22
9.18.4
9.20.1.5
9.18.4.5
9.19.1.24
9.16.4.48
9.18.4.8
9.20.2
9.19.1.27
9.16.4.55
9.18.4.22
9.20.2.10
9.16.4.57
9.19.1.28
9.18.4.24
9.20.2.21
9.16.4.61
9.19.1.31
9.18.4.29
9.20.2.22
9.16.4.62
9.18.4.34
9.20.3
9.16.4.67
9.16.4.70
9.18.4.40
9.23.1
9.22.1.1
9.16.4.71
9.20.3.4
9.18.4.47
9.20.3.7
9.19.1.37
9.16.4.76
9.20.3.9
9.19.1.38
9.18.4.50
9.22.1.3
9.20.3.10
9.22.1.2
9.18.4.52
9.20.3.13
9.22.1.6
9.18.4.53
9.16.4.82
9.22.2
9.20.3.16
9.19.1.42
9.18.4.57
9.16.4.84
9.23.1.3
9.20.3.20
9.22.2.4
9.23.1.7
9.20.4
9.22.2.9
9.23.1.13
9.20.4.7
9.22.2.13
9.18.4.66
9.20.4.10
9.23.1.19
9.16.4.85
9.22.2.14
9.18.4.67
9.24.1
9.18.4.68
9.23.1.22
9.20.4.14
9.22.2.20
9.18.4.71
9.20.4.19
9.23.1.26
9.16.4.89
9.22.2.32
9.18.4.76
9.22.3
9.24.1.5
9.20.4.22
9.24.1.9
9.20.4.28
9.22.3.5
9.16.4.92
9.18.4.135
9.23.1.195
9.20.4.30
9.24.1.155
9.23.1.32
9.24.1.11
9.20.4.34
9.18.4.82
CiscoCisco Secure Firewall Threat Defense (FTD) Software
7.0.0
7.0.0.1
7.0.1
7.0.1.1
7.0.2
7.2.0
7.0.2.1
7.0.3
7.2.0.1
7.0.4
7.2.1
7.0.5
7.3.0
7.2.2
7.2.3
7.3.1
7.2.4
7.0.6
7.2.5
7.2.4.1
7.3.1.1
7.4.0
7.0.6.1
7.2.5.1
7.4.1
7.2.6
7.0.6.2
7.4.1.1
7.2.7
7.2.5.2
7.3.1.2
7.2.8
7.6.0
7.4.2
7.2.8.1
7.0.6.3
7.4.2.1
7.2.9
7.0.7
7.7.0
7.4.2.2
7.2.10
7.6.1
7.4.2.3
7.0.8
7.6.2
7.7.10
7.7.11
7.0.8.1
7.6.2.1
7.7.10.1
7.4.2.4
7.2.10.2
7.4.3
7.6.4
10.0.0
7.4.4
7.0.9
7.2.11
7.4.7
10.0.2

References

1 Links

Record Details

Published
2026-08-11
Last updated
2026-09-16
Assigner (CNA)
cisco
Credited to
-

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