CVE-2024-20353A vulnerability in the management and VPN web servers for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote att…
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It affects Cisco Adaptive Security Appliance (ASA) Software and 4 other products. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Apr 24, 2024; federal agencies had to remediate by May 1, 2024. Treat that date as your deadline.
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A vulnerability in the management and VPN web servers for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower 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 incomplete error checking when parsing an HTTP header. An attacker could exploit this vulnerability by sending a crafted HTTP request to a targeted web server on a device. A successful exploit could allow the attacker to cause a DoS condition when the device reloads.
- CVSS
- 8.6 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- Weakness (CWE)
- CWE-835
- Known exploited
- Added to CISA KEV Apr 24, 2024; federal remediation due May 1, 2024Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- EPSS (exploitation in the next 30 days)
- 70.69% (percentile 99)
- Assigned by
- cisco
- NVD analysis
- Analyzed
- Record last updated
- Oct 21, 2025
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Cisco Cisco Adaptive Security Appliance (ASA) Software cisco:adaptive_security_appliance_asa_software (from the name) | 9.8.1; 9.8.1.5; 9.8.1.7; 9.8.2; 9.8.2.8; 9.8.2.14; 9.8.2.15; 9.8.2.17; and 179 more ranges | CNA record |
Cisco Cisco Firepower Threat Defense Software cisco:firepower_threat_defense_software (from the name) | 6.2.3; 6.2.3.1; 6.2.3.2; 6.2.3.3; 6.2.3.4; 6.2.3.5; 6.2.3.6; 6.2.3.7; and 72 more ranges | CNA record |
cisco asa cisco:asa | from 9.8.1 through 9.8.4.48 | CISA ADP |
cisco firepower_threat_defense_software cisco:firepower_threat_defense_software | from 6.2.3 through 6.2.3.18 | CISA ADP |
cisco adaptive_security_appliance_software cisco:adaptive_security_appliance_software | 9.8.1; 9.8.1.5; 9.8.1.7; 9.8.2; 9.8.2.8; 9.8.2.14; 9.8.2.15; 9.8.2.17; and 179 more ranges | NVD |
cisco secure_firewall_threat_defense cisco:secure_firewall_threat_defense | 6.2.3; 6.2.3.1; 6.2.3.2; 6.2.3.3; 6.2.3.4; 6.2.3.5; 6.2.3.6; 6.2.3.7; and 72 more ranges | NVD |
References
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-websrvs-dos-X8gNucD2vendor-advisory
- https://blog.talosintelligence.com/arcanedoor-new-espionage-focused-campaign-found-targeting-perimeter-network-devices/exploit, third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-20353us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.