SB20260512101 - Multiple vulnerabilities in Microsoft Win32k

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Main Vulnerability Database SB20260512101

SB20260512101 - Multiple vulnerabilities in Microsoft Win32k

Published: May 12, 2026

Security Bulletin ID SB20260512101
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 4
Exploitation vector Local access
Highest impact Code execution

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 4 vulnerabilities.


1) Race condition (CVE-ID: CVE-2026-33839)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear


The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a race condition in Win32k. A local user can exploit the race and gain unauthorized access to sensitive information and escalate privileges on the system.


2) Race condition (CVE-ID: CVE-2026-34331)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear


The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a race condition in Win32k. A local user can exploit the race and gain unauthorized access to sensitive information and escalate privileges on the system.


3) Integer overflow (CVE-ID: CVE-2026-34330)

CWE-ID: CWE-190 - Integer overflow

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear


The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to integer overflow in Windows Win32K - GRFX. A local user can pass specially crafted data to the application, trigger integer overflow and gain elevated privileges on the target system.


4) Use-after-free (CVE-ID: CVE-2026-33840)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear


The vulnerability allows a local user to compromise vulnerable system.

The vulnerability exists due to a use-after-free error in Win32k. A local user can gain elevated privileges on the target system.


Remediation

Install update from vendor's website.

References