EUVD-2026-44098
GHSA-5fc8-2988-xmjx
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Network, unauthenticated, no interaction, but reliable use-after-free exploitation needs heap grooming or a race, so AC:H rather than the published AC:L; impact remains total.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
6DescriptionNVD
Use after free in Microsoft Windows DNS allows an unauthorized attacker to elevate privileges over a network.
AnalysisAI
Privilege elevation via a use-after-free in the Microsoft Windows DNS component lets a network-based, unauthenticated attacker corrupt memory and potentially gain higher privileges on affected Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025 systems. Microsoft rates it CVSS 9.8, and the SSVC assessment lists total technical impact but notes no observed exploitation and that it is not automatable. There is no public exploit identified at time of analysis and it is not on CISA KEV; EPSS is low at 0.67% (48th percentile).
Technical ContextAI
The flaw is a CWE-416 use-after-free in the Windows DNS subsystem - memory is freed and then referenced again, allowing an attacker who controls the reallocated heap contents to influence a dangling pointer and corrupt process state. The affected code ships as part of the Windows platform per the CPE data (cpe:2.3:a:microsoft:windows_11_version_24h2, 25h2, 26h1, and windows_server_2025 including the Server Core installation), meaning both client resolver and Windows Server DNS-role deployments are in scope. Use-after-free bugs in network-facing parsers are a classic memory-corruption primitive: the DNS message/response handling path frees an object while another reference remains live, and subsequent use of that stale reference can be steered toward attacker-controlled data.
RemediationAI
Patch available per vendor advisory: apply the Microsoft security update that raises builds to at least 10.0.26100.8875 (Windows 11 24H2), 10.0.26200.8875 (25H2), 10.0.28000.2269 (26H1), and 10.0.26100.33158 (Windows Server 2025 and its Server Core installation), as published at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50487. Because the fix is delivered through the standard Windows monthly update channel, prioritize domain controllers and any hosts running the DNS Server role, then broadly deploy to client endpoints. If patching a production DNS server must be delayed, reduce exposure by restricting inbound DNS reachability - limit which networks and clients can send DNS queries to the affected server via host firewall or perimeter ACLs, and avoid exposing the Windows DNS service directly to untrusted networks - accepting the trade-off that overly tight filtering can break legitimate resolution for clients or forwarders that rely on that server.
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
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
MSHTML Framework contains a protection mechanism failure (CVE-2026-21513, CVSS 8.8) allowing remote attackers to bypass
Same weakness CWE-416 – Use After Free
View allSame technique Denial Of Service
View allShare
External POC / Exploit Code
Leaving vuln.today