OnlyPatch
Microsoft Brokering File System

CVE-2025-21372 — Microsoft Brokering File System Elevation of Privilege Vulnerability

Important CVSS 7.8 EPSS 0.0039 🔬 Patch diffed 2025-01 archive

Executive Summary

None

Overview

7.8
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
Category Elevation of Privilege
Weakness CWE-416: Use After Free
Released Jan 14 2025
Last Updated Jan 14 2025
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.0039 — 0.31683 percentile
NVD CVSS 7.8 HIGH — matches MSRC

CVSS Vector

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

EPSS Score

0.0039
probability of exploitation in the next 30 days
0.31683 percentile - updated 2026-07-25
View on FIRST.org

Affected Products

5 affected products
Product KB Article Severity Impact Restart Required
Windows 11 Version 24H2 for ARM64-based Systems 5050009 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 24H2 for x64-based Systems 5050009 (Security Update) Important Elevation of Privilege Yes
Windows Server 2022, 23H2 Edition (Server Core installation) 5049984 (Security Update) Important Elevation of Privilege Yes
Windows Server 2025 5050009 (Security Update) Important Elevation of Privilege Yes
Windows Server 2025 (Server Core installation) 5050009 (Security Update) Important Elevation of Privilege Yes

Patches

2 patches
Article Type Restart
5050009 Security Update Yes
5049984 Security Update Yes

Patch Diff

ghidriff · bfs.sys (KB5050009)

Patch diff 10.0.26100.2454 -> 10.0.26100.2894 (per-CVE override for CVE-2025-21372; same bfs.sys diff as bfs_sys-kb5050009.json, with this CVE's own RCA and PoC links)

Pre-patch version 10.0.26100.2454 Download
Post-patch version 10.0.26100.2894 Download
Function Address Change Note
BfsDereferencePolicyEntryEx 1c0004fa0 -> 1c0005160 code, name, fullname, length, sig, address, called similarity 0.92
BfsCheckAndReleaseIdlePolicy 1c0004e00 -> 1c0004ea4 code, length, address, called similarity 0.61
View full diff report View RCA report Download PoC

Known Exploits

Acknowledgments

hazard

On This Page