CVE-2026-61358 — Windows Accessibility Infrastructure (ATBroker.exe) Elevation of Privilege Vulnerability
Executive Summary
Improper link resolution before file access ('link following') in Windows Accessibility Infrastructure (ATBroker.exe) allows an authorized attacker to elevate privileges locally.
Overview
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
EPSS Score
Affected Products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Windows 10 Version 1809 for 32-bit Systems | 5120238 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 10 Version 1809 for x64-based Systems | 5120238 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 10 Version 21H2 for 32-bit Systems | 5120249 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 10 Version 21H2 for ARM64-based Systems | 5120249 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 10 Version 21H2 for x64-based Systems | 5120249 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 10 Version 22H2 for 32-bit Systems | 5120249 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 10 Version 22H2 for ARM64-based Systems | 5120249 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 10 Version 22H2 for x64-based Systems | 5120249 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 11 Version 23H2 for ARM64-based Systems | 5120240 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 11 Version 23H2 for x64-based Systems | 5120240 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 11 Version 24H2 for ARM64-based Systems 5120994 (Security Hotpatch Update) 5121003 (Security Update) Important Elevation of Privilege 5101650 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 10.0.26100.9106 10.0.26100.9168 Yes None Windows 11 Version 24H2 for x64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Important Elevation of Privilege 5101650 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 10.0.26100.9168 10.0.26000.9106 Yes None Windows 11 Version 25H2 for ARM64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Important Elevation of Privilege 5101650 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 10.0.26200.9168 10.0.26100.9106 Yes None Windows 11 Version 25H2 for x64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Important Elevation of Privilege 5101650 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 10.0.26200.9168 10.0.26100.9106 Yes None Windows 11 Version 26H1 for ARM64-based Systems | 5121000 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows 11 version 26H1 for x64-based Systems | 5121000 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows Server 2019 | 5120238 (Security Update) |
Important | Elevation of Privilege | Yes |
| Windows Server 2019 (Server Core installation) | 5120238 (Security Update) |
Important | Elevation of Privilege | Yes |
Patches
| Article | Type | Restart |
|---|---|---|
5120238 |
Security Update | Yes |
5120249 |
Security Update | Yes |
5120240 |
Security Update | Yes |
5121000 |
Security Update | Yes |
Patch Diff
Link-following elevation of privilege (CWE-59) in the Windows Accessibility Infrastructure ATBroker.exe (Assistive Technology Broker), local EoP to SYSTEM (Important, AV:L, CVSS 7.8, Exploitation More Likely). ATBroker copies Assistive-Technology settings between registry locations via SettingsCopier::CopyATSettings / SetRegKeyValue (RegOpenKeyExW -> RegSetValueExW). PRE: the destination key was opened and written WITHOUT checking whether it was a registry symbolic link, so a low-privileged attacker who plants a REG_LINK at the AT-settings target could redirect ATBroker's privileged write to an attacker-chosen key (e.g. a sensitive HKLM location) - link following -> EoP to SYSTEM. Diff of ATBroker.exe 10.0.22621.6783 -> .7219 (Aug 11 2026, KB5120240, Win11 23H2; 24H2 ships the equivalent fix at 10.0.26100.9168 / KB5121003) confirms the fix: the patched CopyATSettings adds an unconditional symbolic-link guard before writing - it opens the key with REG_OPTION_OPEN_LINK (ulOptions=8), queries the special SymbolicLinkValue, and if the key is a registry symbolic link (REG_LINK, type 6) it aborts with a failure HRESULT (0x800705b8) instead of calling RegSetValueExW. The guard is not CFR-gated (ships active in the patched binary).
| Function | Address | Change | Note |
|---|---|---|---|
SettingsCopier::CopyATSettings |
code change |
code (adds registry symbolic-link check before privileged write) | Post: opens the destination key with REG_OPTION_OPEN_LINK (8), queries SymbolicLinkValue; if the key is a REG_LINK (type 6) it aborts (0x800705b8) instead of writing. Pre: opened and wrote the key with no symlink check. |
SettingsCopier::SetRegKeyValue |
code change |
code (write path folded into the guarded CopyATSettings flow) | Pre: RegOpenKeyExW -> RegSetValueExW -> RegCloseKey with no link check. Post: the value write now occurs only after the CopyATSettings symbolic-link check passes. |
Attack Path
A planted registry symbolic link redirects ATBroker's privileged AT-settings write to an attacker-chosen key
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.