Cisco ASAv/FTDv VPN DoS via SSL/TLS Memory Exhaustion
CVE-2024-20260 Published on October 23, 2024

Cisco Adaptive Security Virtual Appliance and Secure Firewall Threat Defense Virtual SSL VPN Denial of Service Vulnerability
Update for September 16, 2026: The original 1.0 version of this advisory was specific to the Cisco Adaptive Security Virtual Appliance (ASAv) and Cisco Secure Firewall Threat Defense Virtual (FTDv) models. However, it was later found that this vulnerability affects all Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software platforms. A vulnerability in the VPN and management web servers of the Cisco Secure Firewall ASA Software and Cisco Secure FTD Software platforms could allow an unauthenticated, remote attacker to cause an affected device to run out of system memory or buffer blocks, which in turn could cause SSL VPN connection processing to slow down and eventually cease altogether. This vulnerability is due to a lack of proper memory management for new incoming SSL/TLS connections. An attacker could exploit this vulnerability by sending a large number of new incoming SSL/TLS connections to the targeted device. A successful exploit could allow the attacker to deplete system memory or buffers, resulting in a denial of service (DoS) condition. The memory or buffers could be reclaimed slowly if the attack traffic is stopped, but a manual reload may be required to restore operations quickly.

NVD

Vulnerability Analysis

CVE-2024-20260 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Type

What is a Stack Exhaustion Vulnerability?

The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.

CVE-2024-20260 has been classified to as a Stack Exhaustion vulnerability or weakness.


Products Associated with CVE-2024-20260

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Cisco Firepower Threat Defense Software
 
Cisco Adaptive Security Appliance Software
 

Affected Versions

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software: Cisco Secure Firewall Threat Defense (FTD) Software: cisco firepower_threat_defense_software: cisco adaptive_security_appliance_software:

Exploit Probability

EPSS
0.62%
Percentile
47.84%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.