CVE-2024-20494
HIGHDescription
A vulnerability in the TLS cryptography functionality of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper data validation during the TLS 1.3 handshake. An attacker could exploit this vulnerability by sending a crafted TLS 1.3 packet to an affected system through a TLS 1.3-enabled listening socket. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: This vulnerability can also impact the integrity of a device by causing VPN HostScan communication failures or file transfer failures when Cisco ASA Software is upgraded using Cisco Adaptive Security Device Manager (ASDM).
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Exploit Intelligence
Moderate risk: more likely to be exploited than 41% of all known CVEs.
References
Related Vulnerabilities
Other CWE-1287 (Improper Validation of Specified Type of Input) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-4879 | Critical | 9.8 | 100% | KEV | - |
| CVE-2022-31007 | Medium | 4.9 | 26% | - | Fix |
| CVE-2024-6298 | Critical | 10.0 | 19% | - | - |
| CVE-2026-25639 | High | 7.5 | 2.5% | - | Fix |
| CVE-2021-43802 | Critical | 9.9 | 2.0% | - | Fix |
| CVE-2024-51550 | Critical | 10.0 | 1.8% | - | Fix |
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-08-01.