CVEs / CVE-2024-20481

CVE-2024-20481: Cisco ASA and FTD Denial-of-Service Vulnerability

• Known exploited in the CISA KEV catalog since 24 Oct 2024
• medium 5.8 CVSS 3.1 (NVD)
• EPSS 15.8% chance of exploitation in the next 30 days, higher than 96% of CVEs (30 Oct 2026)
• Last changed at its sources 11 Aug 2026

Summary

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain a missing release of resource after effective lifetime vulnerability that could allow an unauthenticated, remote attacker to cause a denial-of-service (DoS) of the RAVPN service.

Description

A vulnerability in the Remote Access VPN (RAVPN) service of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) of the RAVPN service. This vulnerability is due to resource exhaustion. An attacker could exploit this vulnerability by sending a large number of VPN authentication requests to an affected device. A successful exploit could allow the attacker to exhaust resources, resulting in a DoS of the RAVPN service on the affected device. Depending on the impact of the attack, a reload of the device may be required to restore the RAVPN service. Services that are not related to VPN are not affected. Cisco Talos discussed these attacks in the blog post Large-scale brute-force activity targeting VPNs, SSH services with commonly used login credentials.

Affected and fixed versions

Exploitation

Severity

References

• CVE-2024-20481 on NVD
• CVE-2024-20481 in the CISA KEV catalog
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-bf-dos-vDZhLqrW (cited by CISA)
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-bf-dos-vDZhLqrW Vendor Advisory
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-20481 US Government Resource