WatchGuard Fireware OS Vulnerable to Remote Code Execution via Stack Buffer Overflow
A critical stack-based buffer overflow vulnerability in WatchGuard Fireware OS, tracked as CVE-2026-13050, allows authenticated attackers to achieve remote code execution.
Zero Day Initiative (ZDI) has disclosed a critical vulnerability affecting WatchGuard's Fireware OS, identified as ZDI-26-500 and assigned CVE-2026-13050. This flaw is a stack-based buffer overflow within the networkd network_wireless_kick_off_user_cb function, which, if exploited, could allow an authenticated attacker to execute arbitrary code on affected devices with root privileges.
The vulnerability stems from a failure to properly validate the length of user-supplied data before it is copied into a fixed-size buffer on the stack. This oversight can be triggered during the handling of wireless client management requests. By sending specially crafted data, an attacker could overwrite adjacent memory on the stack, potentially leading to control flow hijacking and the execution of malicious code.
Exploitation of this vulnerability requires prior authentication to the WatchGuard device. Despite this prerequisite, the potential impact is severe, as successful exploitation grants the attacker root-level access. The Common Vulnerability Scoring System (CVSS) has assigned this vulnerability a score of 7.2, categorizing it as High severity.
WatchGuard has acknowledged the vulnerability and has released security updates to address it. Customers are strongly advised to apply the available patches to mitigate the risk. The company's security advisory, WGSA-2026-00029, provides further details on the affected versions and the remediation steps.
The vulnerability was initially reported to WatchGuard by Nicholas Zubrisky of TrendAI Research on May 22, 2026. The coordinated public release of the advisory occurred on July 29, 2026, with an update to the advisory also published on the same day, indicating ongoing information dissemination and potential refinement of details.
This discovery highlights the persistent threat landscape for network security appliances. Devices like WatchGuard's Fireware OS are critical infrastructure components, and vulnerabilities that allow for remote code execution, even with authentication, pose a significant risk to organizations. The timely patching and awareness of such vulnerabilities are crucial for maintaining robust network security.
While the vulnerability requires authentication, it underscores the importance of securing administrative interfaces and access controls for network devices. Organizations should ensure that only authorized personnel have access to these systems and that strong authentication mechanisms are in place. The disclosure by ZDI and the subsequent patch from WatchGuard represent a crucial step in protecting users from potential exploitation.
This new advisory details a specific stack-based buffer overflow vulnerability, ZDI-26-499, within WatchGuard Fireware OS's CLI token parser that allows for remote code execution. Exploitation requires authentication and results in code execution in the context of the 'nobody' user, with a CVSS rating of 4.7. The vulnerability was reported on May 22, 2026, and publicly disclosed on July 29, 2026, with an update to the advisory also published on the same day.