CVE-2015-1701: Microsoft Windows Win32k.sys Local Privilege Escalation

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 17 September 2026. Confidence: high.

critical priorityThe vulnerability is in CISA KEV with known ransomware use, has a high EPSS score, public exploits, and affects legacy but still deployed Windows systems.

What it is

Win32k.sys in the Windows kernel-mode drivers fails to properly validate input, allowing a local user to elevate privileges by running a crafted application. The flaw was exploited in the wild in April 2015 and is listed in CISA's Known Exploited Vulnerabilities catalog, making it a confirmed real-world risk for unpatched systems.

Impact

An attacker with local access can gain full system privileges, enabling complete control of the affected host. This includes the ability to install programs, view or modify data, and create accounts with full rights.

Attack surface

The vulnerability is reached locally by executing a crafted application on the target system. No user interaction beyond running the application is required, and the attacker must already have a low-privileged local account (CVSS vector AV:L/PR:L/UI:N).

Exploitation

CISA KEV lists this as actively exploited with known ransomware campaign use, and EPSS shows a 30-day probability of 0.562 (99th percentile). Public exploit code exists in Exploit-DB, and FireEye reported probable APT28 use in 2015.

What to do

• Apply the Microsoft security update MS15-051 immediately on all affected Windows versions.
• If patching is not possible, isolate or decommission systems running Windows Server 2003 SP2, Vista SP2, or Server 2008 SP2.
• Restrict local interactive logon and application execution to trusted users only.
• Monitor for and block known exploit binaries or suspicious local privilege escalation attempts.
• Ensure endpoint detection and response tools are updated to flag Win32k privilege escalation behavior.

Detection

• Monitor for processes attempting to load or interact with win32k.sys in unexpected ways, especially from non-system processes.
• Alert on local privilege escalation events where a low-integrity process gains SYSTEM integrity.
• Hunt for known exploit file hashes or names from Exploit-DB entries 37049 and 37367.
• Review Windows security logs for suspicious token manipulation or unexpected SeDebugPrivilege assignment.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.