Cisco ASA/Firepower Threat Defense IKEv2 memory leak

Summaryinfo

A vulnerability categorized as problematic has been discovered in Cisco ASA and Firepower Threat Defense. Affected by this vulnerability is an unknown functionality of the component IKEv2 Handler. Executing a manipulation can lead to memory leak. This vulnerability appears as CVE-2025-20254. The attack may be performed from remote. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Cisco ASA and Firepower Threat Defense (affected version unknown) and classified as problematic. This vulnerability affects an unknown functionality of the component IKEv2 Handler. The manipulation with an unknown input leads to a memory leak vulnerability. The CWE definition for the vulnerability is CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. As an impact it is known to affect availability. CVE summarizes:

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) module of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a memory leak, resulting in a denial of service (DoS) condition. This vulnerability is due to improper parsing of IKEv2 packets. An attacker could exploit this vulnerability by sending a continuous stream of crafted IKEv2 packets to an affected device. A successful exploit could allow the attacker to partially exhaust system memory, causing system instability like being unable to establish new IKEv2 VPN sessions. A manual reboot of the device is required to recover from this condition.

The advisory is shared for download at sec.cloudapps.cisco.com. This vulnerability was named CVE-2025-20254 since 10/10/2024. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/31/2026). The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 331355 (Cisco Firepower Threat Defense (FTD) Software IKEv2 Multiple Vulnerabilities (cisco-sa-asa-ftd-ios-dos-DOESHWHy)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (331355) and CERT Bund (WID-SEC-2025-1838). Once again VulDB remains the best source for vulnerability data.

Affected

• Cisco IOS
• Cisco IOS XE
• Cisco ASA (Adaptive Security Appliance)
• Cisco Secure Firewall Threat Defense

Productinfo

Type

• Firewall Software

Vendor

• Cisco

Name

• ASA
• Firepower Threat Defense

License

• commercial

Website

• Vendor: https://www.cisco.com/

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Once again VulDB remains the best source for vulnerability data.

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