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8.6
CVE-2026-20349
cis · adaptive_security_appliance_software

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

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.

Affected Products

VendorProductVersions
cisadaptive_security_appliance_software9.16.1, 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, 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

Also Affects

Downstream vendors/products affected by this vulnerability

VendorProductSourceConfidence
cisasa (adaptive security appliance)cert_advisory90%
ciscisco secure firewall threat defensecert_advisory90%
cissecure_firewall_threat_defensecve_cpe95%

References

  • https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-dzv4mQFF

Related News (14 articles)

Tier D
SecurityWeek3h ago
Attackers Exploit Second Cisco Firewall VPN Zero-Day Since August
→ No new info (linked only)
Tier D
CSO Online50d ago
September 2026 Patch Tuesday roundup: Plugs for two zero day holes among almost 1,000 fixes in Windows
→ No new info (linked only)
Tier D
The Hacker News69d ago
Cisco Patches Nine Crosswork and Secure Workload Flaws, Five Scoring CVSS 10.0
→ No new info (linked only)
Tier B
CERT-FR73d ago
Bulletin d'actualité CERTFR-2026-ACT-035 (17 août 2026)
→ No new info (linked only)
Tier D
Help Net Security74d ago
Week in review: Salesforce and ServiceNow portals exposed for 17 months, exploited Metabase 0-day
→ No new info (linked only)
Tier B
CCCS Canada77d ago
AL26-018 - Vulnerability affecting Cisco ASA and Secure Firewall Threat Defense Software Remote Access SSL VPN - CVE-2026-20349
→ No new info (linked only)
Tier D
Help Net Security77d ago
Cisco fixes vulnerability exploited to DoS its firewalls (CVE-2026-20349)
→ No new info (linked only)
Tier B
CCCS Canada78d ago
Cisco security advisory (AV26-807)
→ No new info (linked only)
Tier D
Heise Security78d ago
Cisco warnt vor Attacken auf Secure Firewall Adaptive Security Appliance
→ No new info (linked only)
Tier B
BSI Advisories78d ago
[NEU] [hoch] Cisco ASA (Adaptive Security Appliance) und Secure Firewall Threat Defense: Schwachstelle ermöglicht Denial of Service
→ No new info (linked only)
Tier D
The Hacker News78d ago
Cisco ASA and FTD Flaw Exploited in the Wild Can Trigger Remote DoS
→ No new info (linked only)
Tier B
CERT-FR78d ago
Vulnérabilité dans les produits Cisco (12 août 2026)
→ No new info (linked only)
Tier D
BleepingComputer78d ago
Cisco warns of ASA and FTD VPN flaw exploited to crash devices
→ No new info (linked only)
Tier A
Cisco Security78d ago
Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability
→ No new info (linked only)

Discussion (0)

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CVSS 3.18.6 HIGH
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CISA KEV❌ No
Actively exploited❌ No
CWECWE-244
PublishedAug 11, 2026
Trending Score91
Source articles14
Independent10
Info Completeness0/14
Missing: cve_id, title, description, vendor, product, versions, cvss, epss, cwe, kev, exploit, patch, iocs, mitre_attack

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Verification

State: unverified
Confidence: 0%

Vulnerability Timeline

CVE Published
Aug 11, 2026
Discovered by ZDM
Aug 11, 2026