EUVD-2026-35591
GHSA-c2vf-vxwf-338g
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Primary rating from Vendor (microsoft) · only source for this CVE.
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3DescriptionCVE.org
Buffer over-read in Windows Projected File System Filter Driver allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Projected File System (ProjFS) Filter Driver allows an authenticated low-privileged user on a Windows host to escalate to higher privileges by triggering a buffer over-read in the kernel-mode driver. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV, but the CVSS 7.8 with low attack complexity and no user interaction makes it an attractive post-compromise target for endpoint operators.
Technical ContextAI
The Projected File System (ProjFS) is a Windows component that lets user-mode 'providers' project virtual file system content into the namespace on demand - it underpins technologies such as Git's VFS for Git/Scalar and Microsoft Dev Drive scenarios, and is implemented in part by the kernel-mode filter driver prjflt.sys. CWE-125 (out-of-bounds read) indicates that the driver reads past the end of an allocated buffer when handling attacker-supplied input from a local user, which in a kernel filter driver can lead to disclosure of adjacent kernel memory or, depending on how the over-read value is subsequently used, corruption of control flow that yields elevation. The 'Information Disclosure' and 'Buffer Overflow' tags align with this - leaked kernel pointers or token material from an OOB read are commonly chained into a full SYSTEM escalation primitive.
RemediationAI
Apply the Microsoft security update for CVE-2026-42837 from the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42837 - patch available per vendor advisory, though an exact fixed file or KB version is not included in the supplied data, so identify the correct cumulative update for each affected Windows build directly from MSRC. As a temporary compensating control on hosts where patching is delayed, disable the 'Windows Projected File System' optional feature (Disable-WindowsOptionalFeature -Online -FeatureName Client-ProjFS) on machines that do not run Git VFS for Git, Scalar, or Dev Drive workloads, accepting that this will break those specific tools; on systems that need ProjFS, tighten local user execution (AppLocker/WDAC, removal of unnecessary local accounts) so an attacker cannot easily reach the driver's IOCTL surface from low-privileged code.
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Information Disclosure
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External POC / Exploit Code
Leaving vuln.today