OnlyPatch
Windows Storage VSP Driver

CVE-2025-59516 — Windows Storage VSP Driver Elevation of Privilege Vulnerability

Important CVSS 7.8 EPSS 0.02289 🔬 Patch diffed 2025-12 archive

Executive Summary

Missing authentication for critical function in Windows Storage VSP Driver allows an authorized attacker to elevate privileges locally.

Overview

7.8
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
More Likely
MS Exploit Likelihood
Category Elevation of Privilege
Weakness CWE-306: Missing Authentication for Critical Function
Released Dec 9 2025
Last Updated Dec 9 2025
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.02289 — 0.8169 percentile
NVD CVSS 7.8 HIGH — matches MSRC

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
ATTACK VECTOR
Local
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 6.8

EPSS Score

0.02289
probability of exploitation in the next 30 days
0.8169 percentile - updated 2026-08-14
View on FIRST.org

Affected Products

13 affected products
Product KB Article Severity Impact Restart Required
Windows 10 Version 1809 for 32-bit Systems 5071544 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1809 for x64-based Systems 5071544 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for 32-bit Systems 5071546 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for ARM64-based Systems 5071546 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for x64-based Systems 5071546 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 22H2 for 32-bit Systems 5071546 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 22H2 for ARM64-based Systems 5071546 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 22H2 for x64-based Systems 5071546 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 23H2 for ARM64-based Systems 5071417 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 23H2 for x64-based Systems 5071417 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 24H2 for ARM64-based Systems 5072033 (Security Update) 5072014 (Security Hotpatch Update) Important Elevation of Privilege 5068861 5068966 Base: 7.8 Temporal: 6.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 10.0.26100.7462 10.0.26100.7392 Yes None Windows 11 Version 24H2 for x64-based Systems 5072033 (Security Update) 5072014 (Security Hotpatch Update) Important Elevation of Privilege 5068861 5068966 Base: 7.8 Temporal: 6.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 10.0.26100.7462 10.0.26100.7392 Yes None Windows 11 Version 25H2 for ARM64-based Systems 5072033 (Security Update) 5072014 (Security Hotpatch Update) Important Elevation of Privilege 5068861 5068966 Base: 7.8 Temporal: 6.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 10.0.26200.7462 10.0.26200.7392 Yes None Windows 11 Version 25H2 for x64-based Systems 5072033 (Security Update) 5072014 (Security Hotpatch Update) Important Elevation of Privilege 5068861 5068966 Base: 7.8 Temporal: 6.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 10.0.26200.7462 10.0.26200.7392 Yes None Windows Server 2019 5071544 (Security Update) Important Elevation of Privilege Yes
Windows Server 2019 (Server Core installation) 5071544 (Security Update) Important Elevation of Privilege Yes
Windows Server 2022 5071547 (Security Update) 5071413 (Security Hotpatch Update) Important Elevation of Privilege 5068787 5068840 Base: 7.8 Temporal: 6.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 10.0.20348.4529 10.0.20348.4467 Yes None Windows Server 2022 (Server Core installation) 5071547 (Security Update) 5071413 (Security Hotpatch Update) Important Elevation of Privilege 5068787 5068840 Base: 7.8 Temporal: 6.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 10.0.20348.4529 10.0.20348.4467 Yes None Windows Server 2022, 23H2 Edition (Server Core installation) 5071542 (Security Update) Important Elevation of Privilege Yes

Patches

4 patches
Article Type Restart
5071544 Security Update Yes
5071546 Security Update Yes
5071417 Security Update Yes
5071542 Security Update Yes

Patch Diff

ghidriff · storvsp.sys (KB5068861)

Patch diff 10.0.26100.5074 -> 10.0.26100.7171 (VMBus storage; VSMB open-file validation + SG request hardening)

Pre-patch version 10.0.26100.5074
Post-patch version 10.0.26100.7171
Function Address Change Note
VspVsmbFileIoctlVstorVsmbOpenFileValidate 140008430 -> 140008440 code, length, address, called similarity 0.18
VspIsValidSgRequest 140008d54 -> 14000c6d4 code, length, address, called similarity 0.26
VspStartJob 140003a30 length similarity 0.51
StorVspTrace 140003e70 -> 140003e80 refcount, address, calling similarity 1.0
Feature_1128825144__private_IsEnabledDeviceUsageNoInline 14000f2ac -> 14000cad8 name, fullname, refcount, sig, address, calling, called similarity 0.71
View full diff report View RCA report Download PoC

Attack Path

A guest VM opens arbitrary host device objects through the VSMB create path because storvsp.sys never authenticates the caller

Attack path for CVE-2025-59516 A guest VM opens arbitrary host device objects through the VSMB create path because storvsp.sys never authenticates the caller 01 — ENTRY Unauthenticated process inside a Hyper-V guest VM reaches the VSMB channel storvsp.sys (Hyper-V Storage VSP) exposes VSMB to guests via \Device\STORVSP\VSMB. Any guest-side process can issue requests over the channel - no host credentials. 02 — CONTROLLED INPUT Guest issues an NtCreateFile-style VSMB create for a host \Device path Handled by VspVsmbFileCreate / VspVsmbCommonRelativeCreate. The requested path and flags are fully guest-controlled. 03 — PATH storvsp.sys opens the path with ZwOpenDirectoryObject on the host The create handlers call ZwOpenDirectoryObject directly on \Device paths on behalf of the guest, and VspVsmbGetStatInfo consults a Flags bit while resolving the object. 04 — MISSING CHECK No caller authentication / authorization on the create paths Neither create function validates the guest's privilege level (CWE-306), and a Flags bit in VspVsmbGetStatInfo bypasses the intended access check (CWE-863) - so the guest's request is honoured as if trusted. 05 — PRIMITIVE Guest opens arbitrary host device objects -> guest-to-host elevation of privilege The guest obtains handles to host \Device objects it should never reach, crossing the VM isolation boundary to escalate on the host. The Dec 2025 fix adds strict request-buffer bounds validation in VspVsmbFileIoctlVstorVsmbOpenFileValidate and hardens VspIsValidSgRequest.

Derived from the patch delta: the checks added by the vendor identify which fields crossed a trust boundary unvalidated. Reachability and privilege are taken from the call chain in the RCA report.

Known Exploits

Acknowledgments

Angelboy (@scwuaptx)

On This Page