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High8.6Cisco Exploited

High [CVE-2026-20349] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability

This high-severity Cisco advisory covers CVE-2026-20349 affecting Secure Firewall Adaptive Security Appliance (ASA) Software, Firepower 2100 Series, Firepower 1000 Series.

cisco-sa-asaftd-vpn-dos-dzv4mQFF Published Aug 11, 2026Updated by vendor Aug 11, 2026
CVE-2026-20349
Affected products & platforms
CiscoFirewallASA / FirepowerASA 5500
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Summary

An unauthenticated remote attacker could exploit a flaw in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.

The flaw is caused by insufficient error checking when processing HTTP requests.

Affected products named by the advisory: Firepower 2100 Series; Firepower 1000 Series; ASA 5500-X Series Firewalls; 3000 Series Industrial Security Appliances (ISA); and 3 more.

Affected products named by the advisory: Firepower 9000 Series; Firepower 4100 Series; Adaptive Security Virtual Appliance (ASAv).

Affected versions
  • Scope: This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco Secure Firewall ASA Software or Cisco Secure FTD Software and have one or more of the vulnerable configurations listed in the following table.
  • Release 7.0 (affected unless hot fix Cisco_FTD_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_Hotfix_GC-7.0.9.1-1.sh.REL.tar is installed)
  • Release 7.2 (affected unless hot fix Cisco_FTD_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_HM-7.2.11.1-2.sh.REL.tar is installed)
  • Release 7.4 (affected unless hot fix Cisco_FTD_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_HK-7.4.7.1-1.sh.REL.tar is installed)
  • Release 7.6 (affected unless hot fix Cisco_FTD_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_DD-7.6.4.1-2.sh.REL.tar is installed)
  • Release 7.7 (affected unless hot fix Cisco_FTD_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_Secure_FW_TD_1200_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_AN-7.7.11.1-2.sh.REL.tar is installed)
  • Release 10.0 (affected unless hot fix Cisco_FTD_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_200_Hotfix_R-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_1200_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_6100_Hotfix_S-10.0.0.1-2.sh.REL.tar is installed)
  • Release 9.16 (affected; no hot fix is listed in this advisory)
  • Release 9.18 (affected; no hot fix is listed in this advisory)
  • Release 9.19 (affected; no hot fix is listed in this advisory)
  • Release 9.20 (affected; no hot fix is listed in this advisory)
  • Release 9.22 (affected; no hot fix is listed in this advisory)
  • Release 9.23 (affected; no hot fix is listed in this advisory)
  • Release 9.24 (affected; no hot fix is listed in this advisory)
  • Release 7.3 (affected; no hot fix is listed in this advisory)

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

Fixed versions
  • Release 7.0 — Cisco_FTD_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_Hotfix_GC-7.0.9.1-1.sh.REL.tar
  • Release 7.2 — Cisco_FTD_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_HM-7.2.11.1-2.sh.REL.tar
  • Release 7.4 — Cisco_FTD_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_HK-7.4.7.1-1.sh.REL.tar
  • Release 7.6 — Cisco_FTD_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_DD-7.6.4.1-2.sh.REL.tar
  • Release 7.7 — Cisco_FTD_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_Secure_FW_TD_1200_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_AN-7.7.11.1-2.sh.REL.tar
  • Release 10.0 — Cisco_FTD_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_200_Hotfix_R-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_1200_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_6100_Hotfix_S-10.0.0.1-2.sh.REL.tar

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Install the Cisco hot fix listed for your FMC release train.
  • Release 7.0: install Cisco_FTD_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_GC-7.0.9.1-1.sh.REL.tar / Cisco_FTD_SSP_Hotfix_GC-7.0.9.1-1.sh.REL.tar.
  • Release 7.2: install Cisco_FTD_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_HM-7.2.11.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_HM-7.2.11.1-2.sh.REL.tar.
  • Release 7.4: install Cisco_FTD_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP2K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_FTD_SSP_Hotfix_HK-7.4.7.1-1.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_HK-7.4.7.1-1.sh.REL.tar.
  • Release 7.6: install Cisco_FTD_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_DD-7.6.4.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_DD-7.6.4.1-2.sh.REL.tar.
  • Release 7.7: install Cisco_FTD_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_Secure_FW_TD_1200_Hotfix_AN-7.7.11.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_AN-7.7.11.1-2.sh.REL.tar.
  • Release 10.0: install Cisco_FTD_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_FP1K_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_FP3K_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_FTD_SSP_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_200_Hotfix_R-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_1200_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_4200_Hotfix_S-10.0.0.1-2.sh.REL.tar / Cisco_Secure_FW_TD_6100_Hotfix_S-10.0.0.1-2.sh.REL.tar.
Workaround status
  • There are no workarounds that address this vulnerability.

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

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