CVE-2026-20349 is a vulnerability in the Remote Access SSL VPN service of Cisco Secure Firewall Adaptive Security Appliance (ASA) and Threat Defense (FTD) software, caused by insufficient error checking when processing HTTP requests. An unauthenticated, remote attacker can trigger it by sending a crafted HTTP request to the SSL VPN service on an affected device. A successful exploit causes the device to reload unexpectedly, resulting in a denial-of-service condition; no credentials or user interaction are required, and confidentiality and integrity are not affected. Any organization running ASA or FTD software with the Remote Access SSL VPN service enabled is affected, especially devices whose VPN interface is reachable from the internet. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-08-11 and is reported as exploited in the wild, though no public proof-of-concept is known.
What to do: Upgrade ASA and FTD devices to the fixed releases listed in the Cisco PSIRT advisory for CVE-2026-20349. Until patching is complete, verify whether the Remote Access SSL VPN service is enabled and internet-exposed, restrict access to trusted sources where possible, and check logs for unexpected device reloads. Federal agencies must apply mitigations per CISA BOD 26-04 timelines.
masson the order of 100,000s of internet-exposed ASA/FTD devices (only those with the Remote Access SSL VPN service enabled) — Cisco ASA/FTD is one of the most widely deployed enterprise firewall platforms and public internet scans have historically shown hundreds of thousands of ASA SSL VPN endpoints reachable online, though only devices running the SSL VPN…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
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.
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 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.
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 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 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 patches nine Crosswork and Secure Workload flaws, five rated CVSS 10.0, found internally with no exploitation observed.
Cisco released fixes for four Crosswork platform vulnerabilities including CVE-2026-20030 SQL injection and CVE-2026-20357 missing authentication, both scoring CVSS 10.0, affecting Crosswork Release 7.2.1 and earlier. Five additional flaws in Secure Workload, including CVE-2026-20315 and CVE-2026-20317 at CVSS 10.0, affect SaaS and on-premises deployments up to releases 3.10 and 4.0. All issues were found through internal testing and are not known to be actively exploited. The patches follow a broader internal security review that recently addressed 12 Catalyst SD-WAN and IOS XE bugs.
Weekly digest: exploited Metabase zero-day breached Framework; Salesforce/ServiceNow portals read for 17 months; Microsoft patched 400+ flaws.
Help Net Security's week in review aggregates top stories: a 'City-Forum' campaign tracked by Reco has been pulling records from Salesforce and ServiceNow portals worldwide for 17 months, and Framework suffered a breach via an exploited Metabase zero-day exposing customer contact and IP data. It also covers Microsoft's August 2026 Patch Tuesday fixing 400+ flaws including exploited zero-day CVE-2026-68820, Cisco's fix for exploited firewall DoS bug CVE-2026-20349 (added to CISA KEV), and a second N-able N-central hotfix for actively exploited CVE-2026-18577. Other items include GitHub expanding Dependabot malware alerts to eight package ecosystems and EU AI Act enforcement beginning on 2 August 2026.