OnlyPatch
Windows Cloud Files Mini Filter Driver

CVE-2024-49114 — Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability

Important CVSS 7.8 EPSS 0.00742 🔬 Patch diffed 2024-12 archive

Executive Summary

None

Overview

7.8
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
More Likely
MS Exploit Likelihood
Category Elevation of Privilege
Weakness CWE-820: Missing Synchronization
Released Dec 10 2024
Last Updated Dec 10 2024
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.00742 — 0.51525 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

0.00742
probability of exploitation in the next 30 days
0.51525 percentile - updated 2026-08-14
View on FIRST.org

Affected Products

15 affected products
Product KB Article Severity Impact Restart Required
Windows 10 Version 1809 for 32-bit Systems 5048661 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1809 for x64-based Systems 5048661 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for 32-bit Systems 5048652 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for ARM64-based Systems 5048652 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for x64-based Systems 5048652 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 22H2 for 32-bit Systems 5048652 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 22H2 for ARM64-based Systems 5048652 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 22H2 for x64-based Systems 5048652 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 22H2 for ARM64-based Systems 5048685 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 22H2 for x64-based Systems 5048685 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 23H2 for ARM64-based Systems 5048685 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 23H2 for x64-based Systems 5048685 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 24H2 for ARM64-based Systems 5048667 (Security Update) 5048794 (SecurityHotpatchUpdate) Important Elevation of Privilege 5046617 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 10.0.26100.2605 10.0.26100.2528 Yes No None Windows 11 Version 24H2 for x64-based Systems 5048667 (Security Update) 5048794 (SecurityHotpatchUpdate) Important Elevation of Privilege 5046617 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 10.0.26100.2605 10.0.26100.2528 Yes No None Windows Server 2019 5048661 (Security Update) Important Elevation of Privilege Yes
Windows Server 2019 (Server Core installation) 5048661 (Security Update) Important Elevation of Privilege Yes
Windows Server 2022 5048654 (Security Update) 5048800 (SecurityHotpatchUpdate) Important Elevation of Privilege 5046616 5046698 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 10.0.20348.2966 10.0.20348.2908 Yes None Windows Server 2022 (Server Core installation) 5048654 (Security Update) 5048800 (SecurityHotpatchUpdate) Important Elevation of Privilege 5046616 5046698 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 10.0.20348.2966 10.0.20348.2908 Yes None Windows Server 2022, 23H2 Edition (Server Core installation) 5048653 (Security Update) Important Elevation of Privilege Yes

Patches

4 patches
Article Type Restart
5048661 Security Update Yes
5048652 Security Update Yes
5048685 Security Update Yes
5048653 Security Update Yes

Patch Diff

ghidriff · cldflt.sys (KB5048667)

Missing synchronization (CWE-820) in the Windows Cloud Files minifilter cldflt.sys placeholder-convert / EA path, local EoP to SYSTEM. cldflt.sys (Cloud Files / on-demand files) converts files to/from placeholders and processes extended-attribute (EA) operations against a per-stream context. PRE: HsmFltProcessConvertPlaceholder performed the placeholder conversion without synchronizing against concurrent sync operations on the same stream (and HsmFltPreSET_EA / QueryIfEAExists likewise accessed stream state unsynchronized), so a concurrent operation could modify the placeholder/stream state mid-convert - a missing-synchronization defect that corrupts stream/placeholder state and is exploitable for local EoP to SYSTEM. Diff of cldflt.sys 10.0.26100.2161 -> .2605 (Dec 10 2024, KB5048667) confirms the fix: gated behind CFR flags Feature_401191227 / Feature_3260711228, HsmFltProcessConvertPlaceholder now fetches the stream context (HsmpGetStreamContext) and takes sync-op rundown protection (HsmpAcquireSyncOpRundownProtection) around the conversion, releasing it (HsmpReleaseSyncOpRundownProtection / FltReleaseContext) afterward, and HsmFltPreSET_EA acquires the stream/handle context before operating - serializing placeholder-convert against concurrent sync/EA operations and closing the missing-synchronization window.

Pre-patch version 10.0.26100.2161 Download
Post-patch version 10.0.26100.2605 Download
Function Address Change Note
HsmFltProcessConvertPlaceholder code change code (sync-op rundown protection added, CFR-gated) Post (Feature_401191227): HsmpGetStreamContext(...) then HsmpAcquireSyncOpRundownProtection(streamCtx) around the placeholder conversion; HsmpReleaseSyncOpRundownProtection + FltReleaseContext afterward - serializes convert against concurrent sync operations.
HsmFltPreSET_EA code change code (stream context acquired before EA op, CFR-gated) Post (Feature_3260711228 / Feature_401191227): HsmpGetStreamHandleContext(...) taken before the SET_EA processing, coordinating EA operations with the stream context lifecycle.
QueryIfEAExists code change code (EA existence check updated) Helper updated alongside the EA/convert synchronization rework.
Feature_401191227 / Feature_3260711228 gate added (CFR gate) CFR flags gating the sync-op rundown protection / stream-context acquisition; the original unsynchronized path still ships when disabled.
View full diff report View RCA report

Attack Path

A Cloud Files placeholder conversion runs without synchronization against concurrent stream operations

Attack path for CVE-2024-49114 A Cloud Files placeholder conversion runs without synchronization against concurrent stream operations 01 — ENTRY Local user drives Cloud Files placeholder conversion / EA operations cldflt.sys HsmFltProcessConvertPlaceholder converts a file to/from a placeholder over a per-stream context. AV:L/PR:L/AC:L. 02 — CONTROLLED INPUT Issues concurrent sync/EA operations on the same stream A second operation touches the placeholder/stream state during the conversion. 03 — MISSING CHECK Conversion is not synchronized against concurrent ops (CWE-820) Missing synchronization lets the placeholder/stream state be modified mid-convert. 04 — PATH Stream/placeholder state is corrupted The unsynchronized concurrent modification yields inconsistent/corrupted kernel state. 05 — PRIMITIVE Missing synchronization in the Cloud Files minifilter -> EoP to SYSTEM The Dec 2024 fix (Feature_401191227/3260711228) takes sync-op rundown protection on the stream context around the conversion.

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.

Exploits & PoC

Detection Rules

Acknowledgments

Mateusz Jurczyk with Google Project Zero

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