CVE-2019-1458: Microsoft Windows Win32k memory handling 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 priorityIt is in CISA KEV with known ransomware campaign use and a very high EPSS score, and it grants full system compromise once a local foothold exists.

What it is

Windows Win32k fails to properly handle objects in memory, allowing an elevation of privilege. A local attacker who already has code running on the host can exploit this to gain higher privileges, which matters because the flaw is listed in CISA KEV with known ransomware campaign use.

Impact

An attacker gains elevated privileges on the affected Windows system, potentially reaching SYSTEM-level access. That access can be used to disable defenses, move laterally, or deploy ransomware.

Attack surface

The CVSS vector is local (AV:L) with low privileges required (PR:L) and no user interaction (UI:N), so the attacker must already have a foothold and execute code on the machine. It is not reachable remotely over the network.

Exploitation

CISA added it to KEV on 2022-01-10 with a 2022-07-10 remediation due date and flags known ransomware campaign use; EPSS 30-day probability is 0.74263 (99.462 percentile), and public exploit references exist. Exploitation is confirmed in the wild.

What to do

• Apply the Microsoft security update referenced in the MSRC advisory for CVE-2019-1458 on all affected Windows versions.
• Prioritize patching internet-facing and high-value endpoints, since KEV lists known ransomware use.
• Restrict and monitor local interactive logon and code execution paths to limit the initial foothold this flaw requires.
• Verify patch coverage across all listed products, including Windows 7, 8.1, RT 8.1, Server 2008, 2012, 2016, and Windows 10 1507/1607.

Detection

• Monitor for unexpected privilege escalation to SYSTEM or high-integrity tokens on patched and unpatched hosts.
• Hunt for known public exploit artifacts tied to the WizardOpium and uninitialized-variable privilege escalation proof-of-concepts.
• Alert on suspicious processes spawning from low-privilege contexts that immediately gain elevated access.
• Correlate local exploitation attempts with subsequent ransomware precursor behavior such as defense evasion or credential access.

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