CVE-2025-11838 is a memory corruption vulnerability classified under CWE-763 (Release of Invalid Pointer or Reference) found in WatchGuard Fireware OS versions 12.6.1 up to 12.11.4 and 2025.1 up to 2025.1.2. The flaw exists in the handling of dynamic gateway peers in the Mobile User VPN and Branch Office VPN components when using the IKEv2 protocol. Specifically, the vulnerability allows an unauthenticated attacker to trigger a condition where an invalid pointer or reference is released, leading to memory corruption that causes the affected VPN services to crash, resulting in a denial of service (DoS). The vulnerability does not require any privileges or user interaction, making it remotely exploitable over the network. The CVSS v4.0 base score is 8.7, reflecting the ease of exploitation (network vector, no authentication) and the high impact on availability. No known exploits have been reported in the wild as of the publication date, but the potential for disruption is significant given the critical role of VPNs in secure remote access and branch office connectivity. The vulnerability affects multiple Fireware OS versions commonly deployed in enterprise environments, emphasizing the need for timely patching and configuration review to prevent service disruption.

For European organizations, the impact of CVE-2025-11838 could be substantial, especially for those relying on WatchGuard Fireware OS to secure remote access and branch office VPN connections. A successful exploitation results in denial of service, disrupting VPN connectivity and potentially halting business operations that depend on secure communications. This can affect confidentiality indirectly by forcing fallback to less secure communication methods or causing operational delays. Critical sectors such as finance, healthcare, government, and manufacturing that use WatchGuard devices for VPN services may experience operational downtime, loss of productivity, and increased risk exposure during outages. The unauthenticated nature of the exploit increases the threat surface, allowing attackers to disrupt services without needing credentials or insider access. Although no active exploits are known, the vulnerability’s high severity and ease of exploitation warrant urgent attention to prevent potential attacks that could target European enterprises and public sector organizations.

1. Monitor WatchGuard’s official channels for security advisories and apply patches or firmware updates as soon as they become available to address CVE-2025-11838. 2. In the interim, consider disabling or restricting the use of dynamic gateway peers in IKEv2 VPN configurations if operationally feasible to reduce exposure. 3. Implement network-level access controls to limit exposure of VPN endpoints to trusted IP ranges and reduce the attack surface. 4. Employ intrusion detection and prevention systems (IDS/IPS) to monitor for anomalous traffic patterns targeting VPN services. 5. Conduct regular configuration audits of Fireware OS VPN settings to ensure adherence to security best practices and minimize unnecessary services or features. 6. Develop and test incident response plans to quickly recover from potential DoS events affecting VPN availability. 7. Educate network and security teams about this vulnerability to ensure rapid detection and response to any suspicious activity related to VPN disruptions.