High [CVE-2026-20100 +4] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerabilities
This high-severity Cisco advisory covers CVE-2026-20100 and CVE-2026-20101 and 3 more CVEs affecting Secure Firewall Adaptive Security Appliance (ASA) Software, Firepower 2100 Series, ASA 5500-X Series Firewalls.
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Summary
Multiple vulnerabilities in the Remote Access SSL VPN functionality of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow a remote attacker to cause an affected device to stop responding or to reload unexpectedly, resulting in a denial of service (DoS) condition that may require a manual reboot.
For more information about these vulnerabilities, see the Details section of this advisory.
Affected products named by the advisory: Firepower 2100 Series; ASA 5500-X Series Firewalls; 3000 Series Industrial Security Appliances (ISA); Firepower 9000 Series; and 3 more.
Affected products named by the advisory: Firepower 4100 Series; Adaptive Security Virtual Appliance (ASAv); Firepower 1000 Series.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
Mitigation checklist
- There are no workarounds that address these vulnerabilities.
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
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