CVE-2026-20013: Medium Vulnerability in Cisco Secure Firewall ASA Software & Cisco Secure FTD Software

A vulnerability in the IKEv2 feature of Cisco Secure Firewall ASA Software and Cisco Secure FTD Software could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device that may also impact the availability of services to devices elsewhere in the network. This vulnerability is due to memory exhaustion caused by not freeing memory during IKEv2 packet processing. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. A successful exploit could allow the attacker to exhaust resources, causing a DoS condition that will eventually require the device to manually reload.

The CVSS score of this vulnerability is 5.8, categorized as medium severity. The attack vector is network-based, and the complexity is low, meaning that no special conditions need to be met for an attacker to exploit the vulnerability. Given the potential impact on availability, organizations utilizing affected Cisco products must address this issue promptly.

Risk to organizations includes potential service outages and disruptions, which could affect not only the affected devices but also other services within the network. Therefore, organizations should prioritize patching immediately.

Currently, no public exploit or proof-of-concept (PoC) for this vulnerability has been confirmed, and it has not been classified as actively exploited in the wild.

The publication date of this vulnerability was on March 4, 2026, and the last modification occurred on April 16, 2026. Security teams should regularly monitor for updates regarding this vulnerability and implement the necessary patches and mitigations.

Vulnerability Details

The IKEv2 vulnerability is classified under CWE-401, which pertains to memory exhaustion. Affected products include:

Technical Analysis

The root cause of this vulnerability is memory exhaustion during IKEv2 packet processing. The vulnerability can be exploited by sending crafted IKEv2 packets, which will consume resources on the affected device.

The attack vector is network-based, and the complexity is low. No privileges are required to execute the attack, nor is user interaction necessary. The impact on availability is categorized as low, as the device may require a manual reload to restore functionality.

Risk & Impact Analysis

This vulnerability poses a risk to organizations as it can lead to service outages, potentially affecting other devices within the network. The availability impact being low does not diminish the importance of addressing this vulnerability. Organizations should prioritize patching immediately.

The CVSS score of 5.8 indicates that while the vulnerability is not critical, it is still significant enough to warrant immediate attention. The potential for disruption in service should be taken seriously.

Exploitation Status

Affected Versions

Affected versions for the Cisco Adaptive Security Appliance Software include 9.18.1 - 9.18.4.66, 9.19.1 - 9.20.3.20, 9.22.1.1 - 9.22.2.4, and 9.23.1 - 9.23.1.3. For Cisco Firepower Threat Defense Software, the affected versions are 7.2.0 - 7.2.11, 7.3.0 - 7.4.3, 7.6.0 - 7.6.4, and 7.7.0 - 7.7.10.

Mitigation & Remediation

Organizations should apply patches provided by Cisco to remediate this vulnerability. The necessary updates can be found on the vendor's advisory page. If immediate patching is not feasible, consider implementing network controls to limit exposure. Regular monitoring of network traffic for unusual patterns is also recommended.

For further information on security testing and vulnerability management, organizations can refer to resources on penetration testing and other related practices.

Detection Guidance

Monitor logs for indicators of potential exploitation attempts, focusing on unusual IKEv2 packet patterns and spikes in traffic directed towards affected devices. Behavioral anomalies or sudden resource exhaustion on devices should also be flagged for further investigation.

AppSecure Threat Intelligence Insight

The long-term significance of CVE-2026-20013 lies in its representation of vulnerabilities that can affect network availability. Security teams should learn from this incident to implement better resource management practices within their network infrastructure.

This vulnerability underscores the necessity of robust monitoring systems that can detect and respond to unusual patterns in network traffic. For organizations looking to enhance their security posture, regular penetration testing can play a crucial role.

Additionally, enhancing staff training on recognizing and handling denial-of-service attacks can contribute to a more resilient organization.