Cisco fixes VPN DoS flaw discovered in password spray attacks

Cisco patched CVE-2024-20481, a Remote Access VPN (RAVPN) resource-exhaustion vulnerability in ASA and Firepower Threat Defense that can allow an unauthenticated remote attacker to cause a denial of service by sending large volumes of VPN authentication requests; the flaw was identified during large-scale brute-force credential harvesting campaigns targeting multiple VPN vendors. The advisory notes the service must be enabled for exploitation, provides commands to check for SSL VPN, and also lists additional high-severity Cisco flaws with available patches or mitigations for administrators to apply.