Addressing CVE-2025-9242: WatchGuard Firebox Firewall Vulnerability
Overview of the Vulnerability
WatchGuard Technologies has recently announced critical security updates for its Firebox firewall devices, focusing on a significant vulnerability identified as CVE-2025-9242. This flaw is characterized as an out-of-bounds write issue within the Fireware operating system (OS). Specifically, it poses a risk to systems configured with the IKEv2 VPN protocol, potentially allowing remote attackers to run arbitrary code on the affected devices.
Affected Devices and Fireware OS Versions
The vulnerability primarily impacts Firebox devices operating on Fireware OS versions spanning from 11.x, which has reached its end of life, to 12.x, along with the most recent 2025.1 series. The weakness is found in the iked process, which is responsible for managing VPN connections. If exploited, this flaw could enable unauthorized entities to gain remote execution capabilities without the need for authentication, representing a critical security concern for many organizations.
Advisory Details from WatchGuard
On September 17, 2025, WatchGuard issued a security advisory highlighting that both mobile user connections with IKEv2 and branch office VPNs (BOVPN) employing IKEv2 are potentially vulnerable, especially when set up with dynamic gateway peers. Notably, even if the sensitive IKEv2 VPN settings are removed, the Firebox can still be at risk if it maintains a branch office VPN link to a static gateway peer.
Vulnerable Versions and Recommended Updates
The specific versions of Fireware OS that are impacted include:
- 11.x — End of Life, no additional updates available
- 12.0 through 12.11.3
- 2025.1 series (inclusive of 2025.1.1)
To address this vulnerability, WatchGuard has released patches that include:
- 12.3.1_Update3
- 12.5.13 (for T15 and T35 models)
- 12.11.4
Users are strongly encouraged to upgrade their Firebox appliances to one of these patched versions to mitigate any risks associated with the vulnerability.
Severity and Impact
The vulnerability has been given a CVSS score of 9.3, categorizing it as a severe flaw. This rating underscores the potential consequences of an attack, as an unauthenticated remote attacker could execute arbitrary code. Such a breach could lead to complete compromise of the firewall as well as the network it is designed to protect. This risk is particularly pertinent for organizations that depend on Firebox firewalls for secure VPN access through the IKEv2 protocol.
Temporary Workaround Measures
For administrators who may not be able to implement the updates immediately, WatchGuard provides a temporary workaround aimed at securing devices that are vulnerable due to their configuration with Branch Office VPN tunnels linked to static gateway peers.
Key actions include:
- Disabling Dynamic Peer BOVPNs: Remove any VPN tunnels that utilize dynamic gateway peers.
- Creating Aliases: Establish groups for trusted static IP addresses that correspond to remote BOVPN peers.
- Adding New Firewall Policies: Allow VPN traffic (including UDP port 500, UDP 4500, AH, and ESP) exclusively from the defined aliases.
- Disabling Default VPN Policies: Turn off built-in IPSec policies that permit all incoming VPN connections.
These steps can help limit exposure until an official patch can be applied.
Importance of Updates and Security Management
The advisory from WatchGuard (WGSA-2025-00015) emphasizes the critical nature of this vulnerability. The advisory warns: “An Out-of-bounds Write vulnerability in the WatchGuard Fireware OS iked process may allow a remote unauthenticated attacker to execute arbitrary code.” The company urges users to prioritize these security updates due to the elevated severity of the risk.
Organizations utilizing WatchGuard Firebox devices need to act promptly by upgrading to the secured Fireware OS versions to effectively manage and mitigate the potential threats linked to CVE-2025-9242. By taking these actions, businesses can enhance their network security and protect against unauthorized access.
