OnlyPatch
Microsoft Bluetooth Driver

CVE-2022-35820 — Windows Bluetooth Driver Elevation of Privilege Vulnerability

Important CVSS 7.8 EPSS 0.00557 🔬 Patch diffed 2022-08 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
Released Aug 9 2022
Last Updated Aug 9 2022
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.00557 — 0.43654 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

0.00557
probability of exploitation in the next 30 days
0.43654 percentile - updated 2026-08-14
View on FIRST.org

Affected Products

25 affected products
Product KB Article Severity Impact Restart Required
Windows 10 for 32-bit Systems 5016639 (Security Update) Important Elevation of Privilege Yes
Windows 10 for x64-based Systems 5016639 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1607 for 32-bit Systems 5016622 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1607 for x64-based Systems 5016622 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1809 for 32-bit Systems 5016623 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1809 for ARM64-based Systems 5016623 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 1809 for x64-based Systems 5016623 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 20H2 for 32-bit Systems 5016616 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 20H2 for ARM64-based Systems 5016616 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H1 for 32-bit Systems 5016616 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H1 for ARM64-based Systems 5016616 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H1 for x64-based Systems 5016616 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for 32-bit Systems 5016616 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for ARM64-based Systems 5016616 (Security Update) Important Elevation of Privilege Yes
Windows 10 Version 21H2 for x64-based Systems 5016616 (Security Update) Important Elevation of Privilege Yes
Windows 11 version 21H2 for ARM64-based Systems 5016629 (Security Update) Important Elevation of Privilege Yes
Windows 11 version 21H2 for x64-based Systems 5016629 (Security Update) Important Elevation of Privilege Yes
Windows 7 for 32-bit Systems Service Pack 1 5016676 (Monthly Rollup) 5016679 (Security Only) Important Elevation of Privilege 5015861 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 6.1.7601.26065 Yes 5016676 5016679 Windows 7 for x64-based Systems Service Pack 1 5016676 (Monthly Rollup) 5016679 (Security Only) Important Elevation of Privilege 5015861 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 6.1.7601.26065 Yes 5016676 5016679 Windows 8.1 for 32-bit systems 5016681 (Monthly Rollup) 5016683 (Security Only) Important Elevation of Privilege 5015874 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 6.3.9600.20520 Yes None Windows 8.1 for x64-based systems 5016681 (Monthly Rollup) 5016683 (Security Only) Important Elevation of Privilege 5015874 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 6.3.9600.20520 Yes None Windows RT 8.1 5016681 (Monthly Rollup) Important Elevation of Privilege Yes
Windows Server 2008 R2 for x64-based Systems Service Pack 1 5016676 (Monthly Rollup) 5016679 (Security Only) Important Elevation of Privilege 5015861 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 6.1.7601.26065 Yes 5016676 5016679 Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 5016676 (Monthly Rollup) 5016679 (Security Only) Important Elevation of Privilege 5015861 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 6.1.7601.26065 Yes 5016676 5016679 Windows Server 2012 5016672 (Monthly Rollup) 5016684 (Security Only) Important Elevation of Privilege 5015863 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 6.2.9200.23817 Yes None Windows Server 2012 (Server Core installation) 5016672 (Monthly Rollup) 5016684 (Security Only) Important Elevation of Privilege 5015863 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 6.2.9200.23817 Yes None Windows Server 2012 R2 5016681 (Monthly Rollup) 5016683 (Security Only) Important Elevation of Privilege 5015874 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 6.3.9600.20520 Yes None Windows Server 2012 R2 (Server Core installation) 5016681 (Monthly Rollup) 5016683 (Security Only) Important Elevation of Privilege 5015874 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 6.3.9600.20520 Yes None Windows Server 2016 5016622 (Security Update) Important Elevation of Privilege Yes
Windows Server 2016 (Server Core installation) 5016622 (Security Update) Important Elevation of Privilege Yes
Windows Server 2019 5016623 (Security Update) Important Elevation of Privilege Yes
Windows Server 2019 (Server Core installation) 5016623 (Security Update) Important Elevation of Privilege Yes
Windows Server 2022 5016627 (Security Update) Important Elevation of Privilege Yes
Windows Server 2022 (Server Core installation) 5016627 (Security Update) Important Elevation of Privilege Yes
Windows Server, version 20H2 (Server Core Installation) 5016616 (Security Update) Important Elevation of Privilege Yes

Patches

7 patches
Article Type Restart
5016639 Security Update Yes
5016622 Security Update Yes
5016623 Security Update Yes
5016616 Security Update Yes
5016629 Security Update Yes
5016681 Monthly Rollup Yes
5016627 Security Update Yes

Patch Diff

ghidriff · bthport.sys (KB5016616)

Registry-symlink local EoP (CWE-285 improper authorization) in the Windows Bluetooth core driver bthport.sys (Pwn2Own 2022 Win11 EoP). Issuing IOCTL 0x41104C to the CLUSPORT... no: to the Bluetooth device object calls HCI_SetLocalServiceInfo -> HCI_GetLocalServiceKey, which creates registry keys (local service info) without OBJ_FORCE_ACCESS_CHECK, so a low-privileged user can plant a registry symbolic link and force the SYSTEM driver to create/modify arbitrary HKLM keys -> EoP. IN-HOUSE ghidriff of bthport.sys 10.0.19041.1682 -> .1889 (Aug 9 2022) confirms the fix: a new BthCreateKeyEx helper (access-checked key creation) and Microsoft::Bluetooth::BthCoreCx::Driver::UpdateRegistryKeysSecurity are added, and the HCI_RegUpdate* / local-service-key registry paths are reworked to use them so key creation is access-checked and not symlink-followable. Reporter: submitted via Pwn2Own 2022.

Pre-patch version 10.0.19041.1682 Download
Post-patch version 10.0.19041.1889 Download
Function Address Change Note
BthCreateKeyEx added (new helper) added (access-checked registry create) New wrapper for registry key creation added in the fix; replaces raw create calls on the Bluetooth registry paths so the create is access-checked (OBJ_FORCE_ACCESS_CHECK) and does not follow user-planted symlinks.
Microsoft::Bluetooth::BthCoreCx::Driver::UpdateRegistryKeysSecurity changed/added code (tightens key security) Reworks the security applied to Bluetooth registry keys as part of the fix.
HCI_RegUpdate* / HCI_GetLocalServiceKey path changed code (use access-checked create) The HCI registry-update paths (reached from HCI_SetLocalServiceInfo->HCI_GetLocalServiceKey via IOCTL 0x41104C) are updated to use BthCreateKeyEx instead of unchecked ZwCreateKey.
View full diff report View RCA report

Attack Path

A Bluetooth IOCTL creates local-service registry keys without an access check, following a user symlink to write arbitrary HKLM as SYSTEM

Attack path for CVE-2022-35820 A Bluetooth IOCTL creates local-service registry keys without an access check, following a user symlink to write arbitrary HKLM as SYSTEM 01 — ENTRY Low-privileged user opens the Bluetooth device (\Device symbolic link) and issues IOCTL 0x41104C bthport.sys (Bluetooth core, kernel/SYSTEM) exposes a device link usable by low-priv processes; IOCTL 0x41104C reaches HCI_SetLocalServiceInfo. 02 — CONTROLLED INPUT HCI_SetLocalServiceInfo -> HCI_GetLocalServiceKey creates a registry key for local service info The driver creates keys under its Bluetooth registry area on behalf of the caller. 03 — PATH The key is created with ZwCreateKey but without OBJ_FORCE_ACCESS_CHECK The create runs with the driver's SYSTEM authority and does not evaluate the caller. 04 — MISSING CHECK No access check / symlink validation on the create A user who can create the target subkey plants a registry symbolic link; the SYSTEM create follows it (CWE-285). 05 — PRIMITIVE SYSTEM creates/modifies arbitrary HKLM keys -> EoP The symlink redirects the SYSTEM create to a protected HKLM location. The Aug 2022 fix adds BthCreateKeyEx (access-checked create) + UpdateRegistryKeysSecurity.

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

T0 working with Trend Micro Zero Day Initiative

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