CVE-2019-1215: Windows Winsock ws2ifsl.sys 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.

high priorityIt is a confirmed exploited local privilege escalation with known ransomware use, but it requires an existing foothold on the host, which limits it below critical.

What it is

ws2ifsl.sys, the Winsock IFS layer driver, mishandles objects in memory, allowing a local user to escalate privileges. Microsoft rates it high severity (CVSS 3.1 7.8), and it affects a wide range of Windows client and server releases. It matters because it is a confirmed exploited-in-the-wild local privilege escalation, a common step in ransomware chains.

Impact

An attacker who already has code execution as a low-privileged user gains full control of the affected system, including high confidentiality, integrity and availability impact. In practice this enables disabling defenses, dumping credentials and deploying ransomware.

Attack surface

The vector is local (AV:L) with low privileges required (PR:L) and no user interaction (UI:N), so the attacker must already run code on the host and then trigger the vulnerable driver. It is not remotely reachable and needs no victim action.

Exploitation

CVE-2019-1215 is listed in CISA KEV with known ransomware campaign use, and EPSS shows a 19.25% 30-day probability (97th percentile), indicating active exploitation. References are limited to the Microsoft patch advisory and the CISA KEV entry.

What to do

• Apply the Microsoft security update for CVE-2019-1215 on all affected Windows client and server versions; treat this as the first action.
• Prioritize internet-facing and high-value hosts, and any system where a non-admin user can run code, for immediate patching.
• Restrict local interactive logon and code execution rights to reduce the pool of accounts that can reach the vulnerable driver.
• Monitor for and block known post-exploitation tooling and ransomware behavior on unpatched endpoints.
• Track KEV remediation due dates and verify patch compliance across the full affected product list.

Detection

• Alert on unexpected loads or abuse of ws2ifsl.sys and other Winsock IFS drivers outside normal system activity.
• Hunt for privilege escalation from medium-integrity processes to SYSTEM, especially spawning of cmd.exe, powershell.exe or service creation shortly after user-level execution.
• Correlate local exploit attempts with subsequent credential dumping, defense evasion or ransomware precursor activity.
• Audit hosts still missing the September 2019 Microsoft cumulative updates and flag them for remediation.

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