# Critical WatchGuard Agent for Windows Flaws (CVE-2026-57910, CVE-2026-57909) Enable Unauthenticated SYSTEM-Level RCE

> WatchGuard disclosed two critical vulnerabilities in WatchGuard Agent for Windows versions earlier than 1.25.13.0000: an improper-authentication flaw in the UDP discovery/command service (CVE-2026-57910, CVSS v4.0 9.3) that lets an unauthenticated network attacker abuse the agent's TaskExecute event handler to download and execute an attacker-controlled program, and a path-traversal flaw (CVE-2026-57909, CVSS v4.0 9.4) reachable from an adjacent network that lets a malicious process drop an unauthorized executable. Both yield arbitrary code execution with SYSTEM privileges on an endpoint-security agent with a broad enterprise install base.

- **Published:** 2026-08-27T00:00:00Z
- **Last reviewed:** 2026-08-30T14:48:45.805Z
- **Canonical:** https://intel.threadlinqs.com/threat/TL-2026-2162
- **ID:** TL-2026-2162
- **Severity:** CRITICAL (CVSS 9.4)
- **Category:** VULNERABILITY
- **Status:** ACTIVE
- **Detections:** 9 · **IOCs:** 18 (full data via the Threadlinqs MCP server — Purple tier)
- **CVEs:** CVE-2026-57910, CVE-2026-57909

## Description

On 2026-08-25 WatchGuard's PSIRT disclosed CVE-2026-57910 and CVE-2026-57909, two critical vulnerabilities in WatchGuard Agent for Windows versions prior to 1.25.13.0000, documented in security advisory WGSA-2026-00012 ('WatchGuard Agent on Windows Privilege Escalation Vulnerability').

CVE-2026-57910 (CVSS v4.0 9.3, CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N) is an improper-authentication weakness (CWE-306) in the agent's UDP discovery and command service. An unauthenticated attacker with network access can abuse this service to trigger the agent's TaskExecute event handler, instructing the agent to download and execute an attacker-controlled program. Two additional weaknesses compound the flaw: the agent does not correctly verify a cryptographic signature on the fetched payload before running it (CWE-347), and it downloads code without an integrity check (CWE-494). WatchGuard's own PSIRT record maps CVE-2026-57910 to both CAPEC-115 (Authentication Bypass) and CAPEC-242 (Code Injection). NVD's Stakeholder-Specific Vulnerability Categorization (SSVC) for the CVE rates exploitation status as 'none' (no observed in-the-wild activity), automatable as 'yes' (the exploitation steps can be scripted/scaled without human tailoring), and technical impact as 'total' (full loss of confidentiality, integrity, and availability of the affected component). Because the WatchGuard Agent service runs with elevated (SYSTEM) privileges on Windows, the net effect is unauthenticated, network-reachable, SYSTEM-level code execution requiring no user interaction.

CVE-2026-57909 (CVSS v4.0 9.4, CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H) is a path-traversal flaw (CWE-94, with the same missing-authentication root cause, CWE-306) that lets a malicious process on an adjacent network segment drop an unauthorized executable file onto the host outside the directory the agent intended, again resulting in arbitrary code execution with SYSTEM privileges. Its CVSS vector requires Adjacent Network (AV:A) rather than the unrestricted Network (AV:N) access of CVE-2026-57910, but scores slightly higher (9.4 vs 9.3) because NVD/WatchGuard also record subsequent-system impact (SC:H/SI:H/SA:H) — successful exploitation can propagate beyond the initially compromised host. Independent technical write-ups characterize the adjacency requirement as reducing pure internet-facing exposure while remaining significant in enterprise settings, since an attacker can reach an adjacent segment via a compromised endpoint, a rogue/compromised Wi-Fi or VPN access point, or prior lateral movement.

WatchGuard states it is not aware of either vulnerability being exploited in the wild as of the 2026-08-25 disclosure date, and CVE-2026-57910/57909 do not appear in CISA's Known Exploited Vulnerabilities catalog as of 2026-08-26. No public proof-of-concept or discoverer credit was found for CVE-2026-57910; CVE-2026-57909 is credited to researcher 'R31nfinder' per WatchGuard's PSIRT page. WatchGuard Agent for Windows 1.25.13.0000 (released 2026-08-19) resolves both issues; for CVE-2026-57910 only, the legacy branches 1.17.02.0000 and 1.17.21.0000 are also listed as fixed. Because the WatchGuard Agent is itself an endpoint-security product running with SYSTEM privileges and a broad enterprise footprint, an attacker who reaches the vulnerable UDP service on an unpatched host can achieve full host compromise (malware installation, persistence, tampering with the security agent's own protective configuration, credential/file access, and a foothold for lateral movement) without any authentication step. Independent security-media analysis published alongside the advisories converges on the same monitoring guidance: watch for unusual UDP discovery-service traffic, unexpected TaskExecute event-handler activity, and suspicious/unsigned binary downloads or file drops performed by the WatchGuard Agent process outside its expected install directories.

## MITRE ATT&CK

- T1190 Exploit Public-Facing Application
- T1569 System Services
- T1553 Subvert Trust Controls
- T1685 Disable or Modify Tools
- T1046 Network Service Discovery
- T1588 Obtain Capabilities
- T1595.002 Active Scanning
- T1587.001 Develop Capabilities
- T1569.002 System Services
- T1543.003 Create or Modify System Process
- T1068 Exploitation for Privilege Escalation
- T1553.002 Subvert Trust Controls
- T1562.001 Impair Defenses
- T1210 Exploitation of Remote Services
- T1005 Data from Local System
- T1105 Ingress Tool Transfer

## Sources

- [WatchGuard PSIRT — CVE-2026-57910 (Improper Authentication)](https://psirt.watchguard.com/CVE-2026-57910/)
- [WatchGuard PSIRT — CVE-2026-57909 (Path Traversal)](https://psirt.watchguard.com/CVE-2026-57909/)
- [WatchGuard Agent on Windows Privilege Escalation Vulnerability (WGSA-2026-00012)](https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00012)
- [NVD — CVE-2026-57910](https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-57910)
- [NVD — CVE-2026-57909](https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-57909)
- [Critical WatchGuard Agent for Windows Vulnerability Let Attackers Execute Remote Code](https://cybersecuritynews.com/watchguard-agent-for-windows-vulnerability/)
- [WatchGuard Agent Vulnerabilities Let Attackers Grant Full SYSTEM Privileges on Windows](https://cybersecuritynews.com/watchguard-agent-vulnerabilities-windows/)
- [Critical WatchGuard Agent Flaws Let Unauthenticated Attackers Execute Remote Code](https://gbhackers.com/critical-watchguard-agent-flaws/)
- [Critical WatchGuard Agent Flaws Let Remote Attackers Execute Arbitrary Code](https://cyberpress.org/critical-watchguard-agent-flaws-2/)
- [WatchGuard Agent Releases (release notes)](https://www.watchguard.com/support/release-notes/cloud/Content/en-US/WatchGuard-Cloud/EN_wg-agent-releases.html)
- [CISA Known Exploited Vulnerabilities Catalog](https://www.cisa.gov/known-exploited-vulnerabilities-catalog)

## Full data

Detection queries (Splunk SPL / Microsoft KQL / Sigma) and IOC values require the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp

Canonical: https://intel.threadlinqs.com/threat/TL-2026-2162