Advisory Details

May 12th, 2026

Microsoft Windows splwow64 Race Condition Local Privilege Escalation Vulnerability

ZDI-26-310
ZDI-CAN-28605

CVE ID CVE-2026-34342
CVSS SCORE 4.4, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Windows
VULNERABILITY DETAILS

This vulnerability allows local attackers to escalate privileges on affected installations of Microsoft Windows. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the splwow64.exe process, which is part of the Print Spooler service. The issue results from unsafe use of shared memory. An attacker can leverage this vulnerability to escalate privileges from low integrity and execute arbitrary code in the context of the current user at medium integrity.

ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34342
DISCLOSURE TIMELINE
  • 2026-01-12 - Vulnerability reported to vendor
  • 2026-05-12 - Coordinated public release of advisory
  • 2026-05-12 - Advisory Updated
CREDIT Marcin Wiazowski
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