Full Report
WatchGuard security advisory (AV26-428)
Analysis Summary
# Vulnerability: Multiple Privilege Escalation and Buffer Overflow Flaws in WatchGuard Agent for Windows
## CVE Details
- **CVE ID:** CVE-2026-6787, CVE-2026-6788, CVE-2026-41288, CVE-2026-41286, CVE-2026-41287
- **CVSS Score:** Not explicitly listed in the advisory summary (Typically High for SYSTEM escalation and DoS)
- **CWE:** CWE-121 (Stack-based Buffer Overflow), CWE-269 (Improper Privilege Management)
## Affected Systems
- **Products:** WatchGuard Agent on Windows
- **Versions:** Version 1.25.02.0000 and all prior versions
- **Configurations:** Systems with the WatchGuard Agent Service or Discovery Service actively running.
## Vulnerability Description
This advisory addresses three primary security issues within the WatchGuard Agent for Windows:
1. **Local Privilege Escalation (LPE) to SYSTEM:** CVE-2026-6787 and CVE-2026-6788 involve chained vulnerabilities within the Agent Service that allow a local user to escalate privileges to the SYSTEM level.
2. **Additional Privilege Escalation:** CVE-2026-41288 identifies a separate path for privilege escalation within the agent software.
3. **Denial of Service (DoS):** CVE-2026-41286 and CVE-2026-41287 involve stack-based buffer overflows in the WatchGuard Agent Discovery Service. These flaws (Variants A and B) can be triggered to crash the service, leading to a loss of functionality.
## Exploitation
- **Status:** Not explicitly reported as exploited in the wild; however, the nature of these flaws suggests they are viable for research-based exploitation.
- **Complexity:** Medium (LPE often requires chaining; DoS requires specifically crafted packets).
- **Attack Vector:**
- **Local:** For Privilege Escalation (CVE-2026-6787, 6788, 41288).
- **Network/Adjacent:** Potential for Discovery Service DoS (CVE-2026-41286, 41287) depending on service exposure.
## Impact
- **Confidentiality:** High (Full SYSTEM access via LPE allows access to all data).
- **Integrity:** High (SYSTEM access allows for complete system modification).
- **Availability:** High (Stack-based overflows cause service crashes/Denial of Service).
## Remediation
### Patches
WatchGuard recommends updating to the latest version of the WatchGuard Agent for Windows (versions subsequent to 1.25.02.0000).
- **Recommended Action:** Update to the latest patched version available via the WatchGuard Cloud or support portal.
### Workarounds
- **Service Restriction:** Restrict local user access to agent directories and limit the ability of non-privileged users to interact with service APIs.
- **Network Segmentation:** Ensure the Discovery Service ports are not exposed to untrusted network segments to mitigate DoS risks.
## Detection
- **Indicators of Compromise:** Unusual service restarts of the WatchGuard Agent Discovery Service; presence of unauthorized files in the WatchGuard Agent installation directory; unexpected SYSTEM-level processes spawned by agent-related binaries.
- **Detection methods and tools:** Monitor Windows Event Logs for Service Control Manager errors related to the WatchGuard Agent. Use EDR tools to monitor for privilege escalation patterns involving `WGAgent.exe` or associated services.
## References
- WatchGuard PSIRT Advisory WGSA-2026-00013: [hxxps[:]//www[.]watchguard[.]com/wgrd-psirt/advisory/wgsa-2026-00013]
- WatchGuard PSIRT Advisory WGSA-2026-00012: [hxxps[:]//www[.]watchguard[.]com/wgrd-psirt/advisory/wgsa-2026-00012]
- WatchGuard PSIRT Advisory WGSA-2026-00011: [hxxps[:]//www[.]watchguard[.]com/wgrd-psirt/advisory/wgsa-2026-00011]
- WatchGuard PSIRT Advisory WGSA-2026-00010: [hxxps[:]//www[.]watchguard[.]com/wgrd-psirt/advisory/wgsa-2026-00010]
- Canadian Centre for Cyber Security Alert: [hxxps[:]//www[.]cyber[.]gc[.]ca/en/alerts-advisories/watchguard-security-advisory-av26-428]