Cisco IOS/ASA/IOS XE/Firepower Threat Defense IKEv2 memory leak

Summaryinfo

A vulnerability identified as problematic has been detected in Cisco IOS, ASA, IOS XE and Firepower Threat Defense. This impacts an unknown function of the component IKEv2 Handler. Performing a manipulation results in memory leak. This vulnerability is known as CVE-2025-20239. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Cisco IOS, ASA, IOS XE and Firepower Threat Defense (affected version not known). This affects some unknown functionality of the component IKEv2 Handler. The manipulation with an unknown input leads to a memory leak vulnerability. CWE is classifying the issue as CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. This is going to have an impact on availability. The summary by CVE is:

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) feature of Cisco IOS Software, IOS XE Software, 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 a lack of proper processing of IKEv2 packets. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. In the case of Cisco IOS and IOS XE Software, a successful exploit could allow the attacker to cause the device to reload unexpectedly. In the case of Cisco ASA and FTD Software, a successful exploit could allow the attacker to partially exhaust system memory, causing system instability such as being unable to establish new IKEv2 VPN sessions. A manual reboot of the device is required to recover from this condition.

It is possible to read the advisory at sec.cloudapps.cisco.com. This vulnerability is uniquely identified as CVE-2025-20239 since 10/10/2024. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/17/2025). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2025-1838). Be aware that VulDB is the high quality source for vulnerability data.

Affected

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

Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• ASA
• Firepower Threat Defense
• IOS
• IOS XE

License

• commercial

Website

• Vendor: https://www.cisco.com/

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Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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