WatchGuard Agent Vulnerabilities Let Attackers Grant Full SYSTEM Privileges on Windows

WatchGuard has released urgent security updates to address multiple high-severity vulnerabilities affecting the WatchGuard Agent on Windows.

The most critical of these flaws allows authenticated local attackers to escalate their privileges to the highest system level, granting them complete control over the compromised machine.

Additional vulnerabilities discovered in the software include network-based buffer overflows that can trigger severe denial-of-service conditions.

Chained Local Privilege Escalation

The most severe security advisory, WGSA-2026-00013, highlights two vulnerabilities: CVE-2026-6787 and CVE-2026-6788.

These flaws, with a high CVSS score of 8.5, involve chained agent service vulnerabilities in the Windows client.

When an attacker successfully links these exploits together, they can execute a local privilege escalation attack to gain NT AUTHORITYSYSTEM access.

Obtaining this level of unrestricted access enables threat actors to turn off security monitoring tools, deploy persistent malware, extract sensitive endpoint data, or create new hidden administrative accounts.

Another significant privilege escalation vulnerability, tracked as CVE-2026-41288, holds a CVSS score of 7.3.

This specific flaw stems from an incorrect permission assignment within the patch management component of the WatchGuard Agent.

An authenticated local user can exploit this structural misconfiguration to seamlessly elevate their privileges from a standard user to SYSTEM level.

This indicates that even a highly restricted, low-privileged employee account could fully compromise the local endpoint device if the software remains unpatched.

Alongside the privilege escalation risks, WatchGuard engineers also addressed two stack-based buffer overflow vulnerabilities residing in the agent’s discovery service.

Tracked under CVE-2026-41286 and CVE-2026-41287, both vulnerability variants carry a CVSS score of 7.1.

Unlike the privilege escalation bugs, which require local access, these overflow flaws allow unauthenticated attackers situated on the same local network to send specially crafted requests that overflow memory buffers.

A successful exploit immediately crashes the agent service, causing a denial-of-service state that temporarily blinds the endpoint’s security management and monitoring capabilities, potentially paving the way for further network attacks.

According to the official WatchGuard advisories, all four vulnerabilities impact the WatchGuard Agent on Windows versions up to and including 1.25.02.0000.

WatchGuard explicitly notes that there are currently no available mitigations or technical workarounds to prevent exploitation without applying the official software patch.

To protect endpoint environments against both local privilege escalation and network-based service disruptions, cybersecurity organizations and IT administrators should immediately update their fleets to WatchGuard Agent on Windows version 1.25.03.0000.

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