Cisco ASA and FTD Flaw Exploited in the Wild Can Trigger Remote DoS
Cisco warns actively exploited flaw CVE-2026-20349 lets unauthenticated attackers crash ASA and FTD firewalls via SSL VPN; CISA added it to KEV.
Cisco fixed CVE-2026-20349 (CVSS 8.6) in Secure Firewall ASA and FTD software, insufficient error checking in HTTP request processing that lets unauthenticated remote attackers force device reloads via crafted requests to the Remote Access SSL VPN service. Hotfixes cover ASA 9.16 through 9.24 and FTD 7.0 through 10.0, and there are no workarounds; Cisco confirmed active exploitation earlier in August but did not name the actor or targets. The flaw was found during internal security testing. CISA added it to the KEV catalog, requiring federal civilian agencies to patch by August 14, 2026.
Cisco ASA and FTD DoS Vulnerability Exploited in the Wild (CVE-2026-20349)
Cisco patched actively exploited high-severity flaw CVE-2026-20349 in ASA and FTD SSL VPN services, allowing unauthenticated remote denial-of-service attacks.
Cisco released a security advisory addressing CVE-2026-20349, a high-severity vulnerability in the Remote Access SSL VPN service of Cisco Secure Firewall ASA and FTD Software. Successful exploitation by an unauthenticated remote attacker can cause affected devices to crash or reload, causing denial of service. The vulnerability is being exploited in the wild, and patches are available; organizations with internet-exposed ASA/FTD VPN endpoints should prioritize updating.
Cisco fixes vulnerability exploited to DoS its firewalls (CVE-2026-20349)
Cisco patches CVE-2026-20349, a high-severity unauthenticated DoS in ASA and FTD VPN services now added to CISA's KEV.
CVE-2026-20349 affects the Remote Access SSL VPN service in Cisco Secure Firewall ASA and FTD software, where specially crafted unauthenticated HTTP requests can cause appliances to reload, creating a denial of service. Cisco confirmed active exploitation observed in August 2026 and released hot fixes for ASA versions 9.16 through 9.24 and FTD versions 7.0 through 10.0. The flaw was added to CISA's Known Exploited Vulnerabilities catalog with a remediation deadline of August 14, 2026 for US civilian federal agencies. No workarounds or indicators of compromise are available.
Cisco security advisory (AV26-197) – Update 3
CISA added Cisco CVE-2026-20079 to its KEV catalog; the Canadian Cyber Centre urges updates across Secure Firewall ASA, FTD, FMC, and SCC products.
The Canadian Centre for Cyber Security updated advisory AV26-197 covering March 2026 Cisco advisories for Security Cloud Control, Secure Firewall Management Center, ASA, and FTD. Cisco confirmed CVE-2026-20131 was actively exploited on March 18, 2026, and CISA added it to KEV on March 19. In Update 3, dated September 9, 2026, CISA added CVE-2026-20079 to the KEV catalog. The underlying flaws include FMC authentication bypass and remote code execution, ASA TCP-flood denial of service, and ASA/FTD IPsec denial of service.
Cisco Advance Notification for Publication of September 16, 2026, Security Advisories
Cisco will publish security advisories with fixed software on September 16, 2026, covering BroadWorks, ISE, Nexus Dashboard, ASA, FMC, FTD and ThousandEyes.
Cisco PSIRT announced advance notification for security advisories to be published on September 16, 2026, along with fixed software releases. Affected products include BroadWorks CommPilot Application Software, Identity Services Engine (ISE), Nexus Dashboard, Secure Firewall ASA, Secure Firewall Management Center (FMC), Secure Firewall Threat Defense (FTD), and ThousandEyes Virtual Appliance. ISE, Nexus Dashboard and the Secure Firewall products receive security hardening releases, and the ASA, FMC and FTD advisories will be included in the same combined release.
Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability
Cisco patched an unauthenticated remote DoS in ASA and FTD Remote Access SSL VPN that reloads devices via crafted HTTP requests.
Cisco disclosed a denial-of-service vulnerability in the Remote Access SSL VPN service of Secure Firewall ASA and FTD software. Insufficient error checking when processing HTTP requests allows an unauthenticated, remote attacker to send a crafted HTTP request that causes the affected device to reload. Cisco has released software updates addressing the flaw.
U.S. CISA adds Metabase, Windows, and Cisco Secure Firewall flaws to its Known Exploited Vulnerabilities catalog.
CISA adds three actively exploited flaws—Cisco ASA/FTD DoS, Windows Winsock SYSTEM-level UAF, and Metabase SQL injection—to its Known Exploited Vulnerabilities catalog.
CISA added CVE-2026-20349 (CVSS 8.6, heap inspection flaw crashing Cisco ASA/FTD via crafted HTTP requests to the Remote Access SSL VPN service), CVE-2026-68820 (CVSS 7.0, use-after-free in the Windows afd.sys Winsock driver allowing SYSTEM-privilege code execution, actively exploited per Microsoft) and CVE-2026-72898 (CVSS 10.0, unauthenticated SQL injection in Metabase) to the KEV catalog. Metabase disclosed its cloud service was attacked with the 0-day, giving the intruder a path to administrator rights and stored credentials for connected databases; cloud instances were patched while self-hosted deployments need urgent updates. Under BOD 22-01, federal civilian agencies must patch by August 14, 2026, except CVE-2026-68820, due August 25.