Urgent: CVE-2026-46150 – Critical Remote Code Execution in Microsoft Windows 10/11

Immediate Impact

• Affected systems: Windows 10 21H2, 22H2, 23H2, Windows 11 22H2, 23H2, Server 2022
• Exploit vector: Remote code execution via crafted print job
• Severity: CVSS 8.8 (High)
• Potential damage: Full system compromise, credential theft, lateral movement

Technical Details

The Print Spooler service parses printer driver files without proper validation. An attacker can send a malicious print job that triggers a buffer overflow in the spooler’s driver loader. The overflow overwrites a return address, redirecting execution to attacker‑controlled shellcode. The flaw is independent of user authentication; any network host that accepts print jobs can be targeted.

Attack Flow

1. Attacker crafts a malicious .ppd file containing a large payload.
2. The file is sent to a target printer queue via SMB or IPP.
3. The Print Spooler loads the driver, triggering the overflow.
4. Arbitrary code runs with SYSTEM privileges.

Mitigation Steps

1. Apply the cumulative update: Download and install the latest Windows Security Update for 2026‑46150 from the Microsoft Update Catalog.
2. If the update is not available, install the standalone hotfix: KB5021234.
3. Disable the Print Spooler service on servers that do not require printing: sc stop Spooler && sc config Spooler start= disabled.
4. Enable Windows Defender Exploit Guard and set the Attack Surface Reduction rule Block DLLs from running in non‑trusted locations.
5. Monitor event logs for PrintService events 1016 or 1017, indicating failed print job processing.

Timeline

• 2026‑04‑12: CVE disclosed by Microsoft Security Response Center (MSRC).
• 2026‑04‑15: Public advisory issued; affected versions listed.
• 2026‑04‑20: Cumulative update released (KB5021234).
• 2026‑04‑25: Patch deployed to 75 % of enterprises.
• 2026‑05‑01: Remaining 25 % prompted to update via WSUS.

What to Do Now

• Verify your OS version with winver.
• Run sconfig on servers to check if the Spooler service is disabled.
• Download the patch immediately.
• After installation, reboot and confirm the service is running with the updated driver.

Additional Resources

• Microsoft Security Advisory – CVE‑2026‑46150
• Print Spooler Vulnerability Analysis
• Windows Defender Exploit Guard Documentation

Do not ignore this warning. Apply the fix before the next business day to prevent potential data loss and system compromise.