EUVD-2026-43900
GHSA-4ffp-3cf5-9hgm
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local low-privileged attacker must win a hard-to-time race (AV:L/PR:L/AC:H) with no user interaction, yielding full SYSTEM compromise (C:H/I:H/A:H) in the same scope (S:U).
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Operating Systems allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in Microsoft Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025 lets an already-authenticated, low-privileged attacker win a race condition (CWE-362) over an improperly synchronized shared resource to elevate privileges. Reported by Microsoft itself, the flaw carries a CVSS 7.0 and per SSVC has total technical impact but is not automatable and shows no observed exploitation; no public exploit is identified at time of analysis. EPSS is low at 0.24% (16th percentile), consistent with the high attack complexity of reliably timing the race.
Technical ContextAI
The root cause is CWE-362, a concurrent-execution race condition arising from a shared resource accessed without proper synchronization inside Windows operating-system components. In a race like this, two or more execution threads operate on the same object (memory structure, handle, file, or kernel object) and the security-relevant check and its use are not atomic, creating a time-of-check to time-of-use window an attacker can exploit by precisely interleaving operations. The CPE data scopes this to core OS platforms - Windows 11 version 24H2, 25H2, and 26H1, plus Windows Server 2025 including the Server Core installation - indicating the vulnerable code lives in the shared Windows kernel/OS servicing branch (build 10.0.26100/26200/28000 families) rather than an add-on application.
RemediationAI
Vendor-released patch: apply the Microsoft cumulative security update that brings each platform to at least the fixed build - Windows 11 24H2 to 10.0.26100.8875, Windows 11 25H2 to 10.0.26200.8875, Windows 11 26H1 to 10.0.28000.2269, and Windows Server 2025 (including Server Core) to 10.0.26100.33158 - via Windows Update, WSUS, or your patch-management pipeline, following the specific KB linked from the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50317. Because this is a race-condition flaw in core OS code, no configuration change fully neutralizes it; patching is the only complete fix. As interim compensating controls until the update is deployed, restrict local logon and interactive access on affected hosts to trusted administrators (limiting who can run the low-privileged code needed to attempt the race), enforce application allowlisting (e.g., WDAC/AppLocker) to reduce the chance of untrusted code executing locally, and prioritize patching multi-user or session-host systems where more low-privilege principals can reach the vulnerable path - noting the trade-off that these access restrictions can disrupt legitimate multi-user or automation workflows.
More in Windows Server 2025
View allWindows Internet Shortcut Files (.url) contain an external control vulnerability (CVE-2025-33053, CVSS 8.8) that enables
Windows SMB contains an improper access control vulnerability (CVE-2025-33073, CVSS 8.8) enabling authenticated attacker
Active Directory Domain Services contains an elevation of privilege vulnerability that allows authenticated domain users
Microsoft Scripting Engine contains a type confusion vulnerability allowing unauthorized remote code execution over the
Windows Task Scheduler Elevation of Privilege Vulnerability. Rated high severity (CVSS 8.8), this vulnerability is low a
Remote code execution in Windows IKE Extension (Internet Key Exchange) via double free memory corruption allows unauthen
Symlink following (CWE-59) in the Windows Update Stack enables a locally authenticated attacker with standard user privi
Local privilege escalation in Microsoft Active Directory Federation Services (AD FS) lets an already-authenticated low-p
A security feature bypass in Microsoft Management Console (MMC) allows attackers to evade security warnings and execute
Privilege escalation in the Windows Ancillary Function Driver for WinSock (afd.sys) allows a locally authenticated attac
Windows CLFS Driver contains an input validation flaw enabling local privilege escalation, yet another CLFS kernel vulne
Windows Ancillary Function Driver for WinSock contains a heap-based buffer overflow enabling local privilege escalation
Same weakness CWE-362 – Race Condition
View allSame technique Information Disclosure
View allShare
External POC / Exploit Code
Leaving vuln.today