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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.
Use CWE-772, Cisco vendor hub and Firepower Threat Defense Software product page to widen CVE-2024-20481 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2026-20103, CVE-2026-20101 and CVE-2026-20039 for nearby disclosures in the same product family. Additional editorial context is available in Weekly Security Roundup: Navigating the April 2026 Threat Landscape and Critical Framework Exploits.