CVE intelligence and bounded remediation

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

Medium CVSS 5.8 CISA KEV

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.

Severity
Medium
CVSS
5.8 (3.1)
Published
2024-10-23
CISA KEV
Known exploited
Ecosystem
software/application
Weaknesses
CWE-772

Affected products

  • cisco / firepower_threat_defense_software / 6.2.3
  • cisco / firepower_threat_defense_software / 6.2.3.1
  • cisco / firepower_threat_defense_software / 6.2.3.2
  • cisco / firepower_threat_defense_software / 6.2.3.3
  • cisco / firepower_threat_defense_software / 6.2.3.4
  • cisco / firepower_threat_defense_software / 6.2.3.5

Showing 6 representative product identities from 289 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Resource exhaustion and denial of service

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify attacker-influenced work factors including input size, nesting, compression, fan-out, regex cost, allocation, recursion, retries, and connection lifetime.
  • Map per-request and shared CPU, memory, disk, descriptor, thread, queue, and downstream-service limits.
  • Determine whether authentication, tenancy, quotas, and rate controls apply before expensive processing begins.

Remediate safely

  • Bound input size, nesting, expansion, work, concurrency, queue depth, retries, and execution time before resource-intensive processing.
  • Release resources on every success, error, cancellation, and timeout path and use backpressure instead of unbounded buffering.
  • Update affected components and add small deterministic tests that assert resource ceilings rather than exhausting a host.

Authoritative sources

Complete CVE record and remediation plan

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