OnlyPatch
Windows Common Log File System Driver

CVE-2022-37969 — Windows Common Log File System Driver Elevation of Privilege Vulnerability

Important CVSS 7.8 EPSS 0.28275 ⚠️ Exploited in the wild 📢 Publicly disclosed 🔬 Patch diffed 2022-09 archive

Executive Summary

None

Overview

7.8
CVSS HIGH
Important
MS Severity
Exploited
MS Exploit Status
Exploitation Detected
MS Exploit Likelihood
Category Elevation of Privilege
Released Sep 13 2022
Last Updated Sep 13 2022
Publicly Disclosed Yes
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.28275 — 0.97949 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

0.28275
probability of exploitation in the next 30 days
0.97949 percentile - updated 2026-08-14
View on FIRST.org

Affected Products

22 affected products
Product KB Article Severity Impact Restart Required
Windows 10 for 32-bit Systems 5017327 (Security Update) Important Elevation of Privilege Yes
Windows 10 for x64-based Systems 5017327 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1607 for 32-bit Systems 5017305 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1607 for x64-based Systems 5017305 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1809 for 32-bit Systems 5017315 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1809 for ARM64-based Systems 5017315 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1809 for x64-based Systems 5017315 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 20H2 for 32-bit Systems 5017308 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 20H2 for ARM64-based Systems 5017308 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H1 for 32-bit Systems 5017308 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H1 for ARM64-based Systems 5017308 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H1 for x64-based Systems 5017308 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for 32-bit Systems 5017308 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for ARM64-based Systems 5017308 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for x64-based Systems 5017308 (Security Update) Important Elevation of Privilege Yes
Windows 11 version 21H2 for ARM64-based Systems 5017328 (Security Update) Important Elevation of Privilege Yes
Windows 11 version 21H2 for x64-based Systems 5017328 (Security Update) Important Elevation of Privilege Yes
Windows 7 for 32-bit Systems Service Pack 1 5017361 (Monthly Rollup) 5017373 (Security Only) Important Elevation of Privilege 5016676 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 6.1.7601.26115 Yes 5017361 5017373 Windows 7 for x64-based Systems Service Pack 1 5017361 (Monthly Rollup) 5017373 (Security Only) Important Elevation of Privilege 5016676 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 6.1.7601.26115 Yes 5017361 5017373 Windows 8.1 for 32-bit systems 5017367 (Monthly Rollup) 5017365 (Security Only) Important Elevation of Privilege 5016681 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 6.3.9600.20571 Yes 5017367 5017365 Windows 8.1 for x64-based systems 5017367 (Monthly Rollup) 5017365 (Security Only) Important Elevation of Privilege 5016681 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 6.3.9600.20571 Yes 5017367 5017365 Windows RT 8.1 5017367 (Monthly Rollup) Important Elevation of Privilege Yes
Windows Server 2008 for 32-bit Systems Service Pack 2 5017358 (Monthly Rollup) 5017371 (Security Only) Important Elevation of Privilege 5016669 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 6.0.6003.21666 Yes 5017358 5017371 Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) 5017358 (Monthly Rollup) 5017371 (Security Only) Important Elevation of Privilege 5016669 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 6.0.6003.21666 Yes 5017358 5017371 Windows Server 2008 for x64-based Systems Service Pack 2 5017358 (Monthly Rollup) 5017371 (Security Only) Important Elevation of Privilege 5016669 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 6.0.6003.21666 Yes 5017358 5017371 Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) 5017358 (Monthly Rollup) 5017371 (Security Only) Important Elevation of Privilege 5016669 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 6.0.6003.21666 Yes 5017358 5017371 Windows Server 2008 R2 for x64-based Systems Service Pack 1 5017361 (Monthly Rollup) 5017373 (Security Only) Important Elevation of Privilege 5016676 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 6.1.7601.26115 Yes 5017361 5017373 Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 5017361 (Monthly Rollup) 5017373 (Security Only) Important Elevation of Privilege 5016676 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 6.1.7601.26115 Yes 5017361 5017373 Windows Server 2012 5017370 (Monthly Rollup) 5017377 (Security Only) Important Elevation of Privilege 5016672 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 6.2.9200.23865 Yes 5017370 5017377 Windows Server 2012 (Server Core installation) 5017370 (Monthly Rollup) 5017377 (Security Only) Important Elevation of Privilege 5016672 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 6.2.9200.23865 Yes 5017370 5017377 Windows Server 2012 R2 5017367 (Monthly Rollup) 5017365 (Security Only) Important Elevation of Privilege 5016681 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 6.3.9600.20571 Yes 5017367 5017365 Windows Server 2012 R2 (Server Core installation) 5017367 (Monthly Rollup) 5017365 (Security Only) Important Elevation of Privilege 5016681 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 6.3.9600.20571 Yes 5017367 5017365 Windows Server 2016 5017305 (Security Update) Important Elevation of Privilege Yes
Windows Server 2016 (Server Core installation) 5017305 (Security Update) Important Elevation of Privilege Yes
Windows Server 2019 5017315 (Security Update) Important Elevation of Privilege Yes
Windows Server 2019 (Server Core installation) 5017315 (Security Update) Important Elevation of Privilege Yes

Patches

6 patches
Article Type Restart
5017327 Security Update Yes
5017305 Security Update Yes
5017315 Security Update Yes
5017308 Security Update Yes
5017328 Security Update Yes
5017367 Monthly Rollup Yes

Patch Diff

ghidriff · clfs.sys (KB5017328)

Windows CLFS Driver Elevation of Privilege. Zero-day vulnerability in clfs.sys used in ITW exploitation. Patch adds validation in container allocation and reset paths.

Pre-patch version 10.0.22000.832 Download
Post-patch version 10.0.22000.978 Download
Function Address Change Note
CClfsBaseFilePersisted::AllocSymbol modified From kb entry
CClfsLogFcbPhysical::ResetLog modified From kb entry
CClfsBaseFilePersisted::LoadContainerQ modified From kb entry
View full diff report View RCA report Download PoC

Attack Path

Kernel pool pointer overwrite via a four-step signature-corruption chain that inflates SignaturesOffset past its bounds check

Attack path for CVE-2022-37969 Kernel pool pointer overwrite via a four-step signature-corruption chain that inflates SignaturesOffset past its bounds check 01 — ENTRY Attacker crafts a .blf and opens it via CreateLogFile Standard user, no special privileges. Same reachability as every other CLFS base-log-file bug. 02 — CONTROLLED INPUT SignaturesOffset=0x50 overlapping the signature array, fake client context, inflated cbSymbolZone rgClients is pointed at a fake Client Context with eState = CLFS_LOG_SHUTDOWN, and cbSymbolZone is set to 0x1114B. 03 — PATH Opening the log walks decode, reset and encode in sequence ClfsDecodeBlockPrivate writes 0x0050 to sector 13's signature slot. ResetLog writes CLFS_LSN_INVALID (0xFFFFFFFF) into the fake client context, landing 0xFFFF on sector 14's signature. ClfsEncodeBlockPrivate then writes that 0xFFFF back into the signature array at offset 0x6C. 04 — MISSING CHECK SignaturesOffset becomes 0xFFFF0050, defeating the cbSymbolZone bounds check in AllocSymbol Nothing revalidates SignaturesOffset after the encode pass mutates it. The patch adds validation on the container-load and reset paths. 05 — PRIMITIVE AddLogContainer -> AllocSymbol -> memset at an inflated offset The memset overwrites the pContainer pointer in an adjacent CLFS_CONTAINER_CONTEXT, giving a controlled kernel pool pointer overwrite, then arbitrary read/write and SYSTEM. Exploited as a zero-day.

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

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