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Findings

CVE-2024-20481

Cisco ASA and FTD Denial-of-Service Vulnerability

Published Oct 23, 2024 · updated Aug 11, 2026 · cisco secure firewall threat defense

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.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2024 · Catalog

    Detected

    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 authenti

  2. Oct 24, 2024 · CISA KEV

    Known exploited

    Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

  3. Nov 14, 2024 · CISA KEV

    Remediation due

    Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

  4. Aug 11, 2026 · Catalog

    Updated

    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 authenti

Required action

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

CISA due date Nov 14, 2024

Affected

  • cpe cisco/adaptive security appliance software9.8.1
  • cpe cisco/secure firewall threat defense6.2.3
  • cpe cisco/secure firewall threat defense6.2.3.1
  • cpe cisco/secure firewall threat defense6.2.3.2
  • cpe cisco/secure firewall threat defense6.2.3.3
  • cpe cisco/secure firewall threat defense6.2.3.4
  • cpe cisco/secure firewall threat defense6.2.3.5
  • cpe cisco/secure firewall threat defense6.2.3.6
  • cpe cisco/secure firewall threat defense6.2.3.7
  • vendor Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)version unspecified

Sources

  • CISA KEVCVE-2024-20481

    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.

    cisa.gov
  • CVE.orgCVE-2024-20481

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2024-20481

    30-day exploitation probability 15.9%

    first.org
  • NIST NVDCVE-2024-20481

    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 vulnerab

    nvd.nist.gov

References