EUVD-2026-44237
GHSA-r7pj-9mj2-wq4v
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local low-privilege attacker (AV:L/PR:L) exploiting a use-after-free race (AC:H) with no interaction, yielding full code-execution-level C/I/A within unchanged scope.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows WebView allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege elevation in the Windows WebView component affects a broad range of currently-supported Windows client and server builds (Windows 10 1809 through Windows 11 26H1, and Windows Server 2019/2022/2025). By triggering a use-after-free (CWE-416) memory-corruption condition, an already-authenticated low-privilege attacker can execute code in a higher-privilege context, yielding full confidentiality, integrity, and availability impact on the local system. Microsoft has released a patch; there is no public exploit identified at time of analysis and the issue is not listed in CISA KEV.
Technical ContextAI
The flaw resides in Windows WebView, the embedded browser/rendering surface used by Windows to host web content inside native applications and shell components. The root cause is a use-after-free (CWE-416): a memory object is freed while a dangling reference remains, and subsequent reuse of that freed allocation lets an attacker control freed memory to corrupt program state. In WebView-class components this class of bug is commonly reached by driving object lifecycle transitions (allocation/free races) during content or DOM handling. The affected CPE set is exclusively Microsoft operating systems spanning Windows 10 (1809, 21H2, 22H2), Windows 11 (23H2, 24H2, 25H2, 26H1), and Windows Server 2019/2022/2025 including Server Core installations, indicating the vulnerable code path ships in the core OS platform rather than a single optional feature.
RemediationAI
Apply the Microsoft security update for CVE-2026-56173 - Patch available per vendor advisory; consult https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56173 for the exact KB and fixed build numbers per affected release, as no single fixed version string was provided in the source data. Deploy through Windows Update / WSUS / Intune / your standard patch pipeline, prioritizing multi-user and interactive-logon hosts (RDS/VDI, jump servers) where a local low-privilege foothold is most likely. No official workaround was published; because this is a local privilege-escalation bug requiring pre-existing low-privilege access, the most effective compensating control until patching is to tighten local access - restrict interactive and service logons to trusted accounts, enforce least privilege, and monitor for unexpected local processes attempting to interact with WebView-hosting applications. These controls reduce opportunity but do not remove the vulnerable code, so patching remains the only complete fix.
More in Windows Server 2019
View allWindows MSHTML component contains a remote code execution vulnerability that allows attackers to craft malicious ActiveX
<p>A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged fi
Windows MSDT (Microsoft Support Diagnostic Tool) allows remote code execution when called via the ms-msdt URL protocol f
Windows Win32k contains an out-of-bounds write vulnerability enabling local privilege escalation to SYSTEM, exploited by
Windows Print Spooler Remote Code Execution Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is no auth
Windows Search Remote Code Execution Vulnerability. Rated high severity (CVSS 7.5), this vulnerability is remotely explo
Internet Shortcut Files Security Feature Bypass Vulnerability. Rated high severity (CVSS 8.1), this vulnerability is rem
Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resour
Windows Kernel contains a TOCTOU race condition vulnerability allowing local privilege escalation, exploited by the OilR
An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in
Active Directory Domain Services Elevation of Privilege Vulnerability. Rated high severity (CVSS 7.5), this vulnerabilit
Windows Internet Shortcut Files (.url) contain an external control vulnerability (CVE-2025-33053, CVSS 8.8) that enables
Same weakness CWE-416 – Use After Free
View allSame technique Denial Of Service
View allShare
External POC / Exploit Code
Leaving vuln.today