CVE-2026-20869: Windows Local Session Manager (LSM) Elevation of Privilege Vulnerability
CVE-2026-20869 is an elevation of privilege vulnerability in Windows Local Session Manager (LSM), rated Important by Microsoft, with a CVSS 3.1 base score of 7 (High). An attacker can exploit it by an attacker with local access, with low privileges and without user interaction. Microsoft has not reported exploitation in the wild and rates exploitation as less likely. The EPSS model estimates a 0.29% probability of exploitation activity in the next 30 days, higher than 22% of all scored vulnerabilities. Microsoft released the fix on 13 January 2026 in the January 2026 Patch Tuesday, delivered through 14 security updates (KB5073723, KB5073457, KB5073724, KB5073379 and more). It affects 35 products in 2 product families (Windows, ESU).
Key facts
- CVE ID
- CVE-2026-20869
- Severity
- High CVSS 7
- Microsoft severity
- Important
- Impact
- Elevation of Privilege
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- Less Likely
- Weakness
- CWE-362
- EPSS
- 0.29% (percentile 22%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- January 2026 Patch Tuesday
- Product families
- Windows, ESU
CVSS score and vector
Microsoft scores CVE-2026-20869 at 7 (temporal 6.1) using CVSS 3.1. Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
| Metric | Value |
|---|---|
| Attack vector | Local |
| Attack complexity | High |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | High |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Description
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Local Session Manager (LSM) allows an authorized attacker to elevate privileges locally.
Frequently asked questions (Microsoft)
According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
Successful exploitation of this vulnerability requires an attacker to win a race condition.
What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.
Affected products (35)
Windows
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 1809 for 32-bit Systems | KB5073723 | Security Update | 10.0.17763.8276 | Yes |
| Windows 10 Version 1809 for x64-based Systems | KB5073723 | Security Update | 10.0.17763.8276 | Yes |
| Windows Server 2019 | KB5073723 | Security Update | 10.0.17763.8276 | Yes |
| Windows Server 2019 (Server Core installation) | KB5073723 | Security Update | 10.0.17763.8276 | Yes |
| Windows Server 2022 | KB5073457 | Security Update | 10.0.20348.4648 | Yes |
| Windows Server 2022 (Server Core installation) | KB5073457 | Security Update | 10.0.20348.4648 | Yes |
| Windows 10 Version 21H2 for 32-bit Systems | KB5073724 | Security Update | 10.0.19044.6809 | Yes |
| Windows 10 Version 21H2 for ARM64-based Systems | KB5073724 | Security Update | 10.0.19044.6809 | Yes |
| Windows 10 Version 21H2 for x64-based Systems | KB5073724 | Security Update | 10.0.19044.6809 | Yes |
| Windows Server 2025 (Server Core installation) | KB5073379 | Security Update | 10.0.26100.32230 | Yes |
| Windows 11 Version 25H2 for ARM64-based Systems | KB5074109 | Security Update | 10.0.26200.7623 | Yes |
| Windows 11 Version 25H2 for x64-based Systems | KB5074109 | Security Update | 10.0.26200.7623 | Yes |
| Windows 11 Version 23H2 for ARM64-based Systems | KB5073455 | Security Update | 10.0.22631.6491 | Yes |
| Windows 11 Version 23H2 for x64-based Systems | KB5073455 | Security Update | 10.0.22631.6491 | Yes |
| Windows Server 2022, 23H2 Edition (Server Core installation) | KB5073450 | Security Update | 10.0.25398.2092 | Yes |
| Windows 11 Version 24H2 for ARM64-based Systems | ||||
| Windows 11 Version 24H2 for x64-based Systems | ||||
| Windows Server 2025 | KB5073379 | Security Update | 10.0.26100.32230 | Yes |
| Windows 10 Version 1607 for 32-bit Systems | KB5073722 | Security Update | 10.0.14393.8783 | Yes |
| Windows 10 Version 1607 for x64-based Systems | KB5073722 | Security Update | 10.0.14393.8783 | Yes |
| Windows Server 2016 | KB5073722 | Security Update | 10.0.14393.8783 | Yes |
| Windows Server 2016 (Server Core installation) | KB5073722 | Security Update | 10.0.14393.8783 | Yes |
ESU
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 22H2 for x64-based Systems | ||||
| Windows 10 Version 22H2 for ARM64-based Systems | ||||
| Windows 10 Version 22H2 for 32-bit Systems | ||||
| Windows Server 2008 for 32-bit Systems Service Pack 2 | KB5073697 KB5073700 | Monthly Rollup Security Only | 6.0.6003.23717 6.0.6003.23717 | Yes Yes |
| Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) | KB5073697 KB5073700 | Monthly Rollup Security Only | 6.0.6003.23717 6.0.6003.23717 | Yes Yes |
| Windows Server 2008 for x64-based Systems Service Pack 2 | KB5073697 KB5073700 | Monthly Rollup Security Only | 6.0.6003.23717 6.0.6003.23717 | Yes Yes |
| Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) | KB5073697 KB5073700 | Monthly Rollup Security Only | 6.0.6003.23717 6.0.6003.23717 | Yes Yes |
| Windows Server 2008 R2 for x64-based Systems Service Pack 1 | KB5073695 KB5073699 | Monthly Rollup Security Only | 6.1.7601.28117 6.1.7601.28117 | Yes Yes |
| Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) | KB5073695 KB5073699 | Monthly Rollup Security Only | 6.1.7601.28117 6.1.7601.28117 | Yes Yes |
| Windows Server 2012 | KB5073698 | Monthly Rollup | 6.2.9200.25868 | Yes |
| Windows Server 2012 (Server Core installation) | KB5073698 | Monthly Rollup | 6.2.9200.25868 | Yes |
| Windows Server 2012 R2 | KB5073696 | Monthly Rollup | 6.3.9600.22968 | Yes |
| Windows Server 2012 R2 (Server Core installation) | KB5073696 | Monthly Rollup | 6.3.9600.22968 | Yes |
Security updates (14)
- KB5073723 (Security Update)
- KB5073457 (Security Update)
- KB5073724 (Security Update)
- KB5073379 (Security Update)
- KB5074109 (Security Update)
- KB5073455 (Security Update)
- KB5073450 (Security Update)
- KB5073722 (Security Update)
- KB5073697 (Monthly Rollup)
- KB5073700 (Security Only)
- KB5073695 (Monthly Rollup)
- KB5073699 (Security Only)
- KB5073698 (Monthly Rollup)
- KB5073696 (Monthly Rollup)
NIST NVD data
- NVD status
- Analyzed
- NVD CVSS
- 7 (HIGH)
- NVD weakness
- CWE-362
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| windows 10 1607 (x64) | before 10.0.14393.8783 |
| windows 10 1607 (x86) | before 10.0.14393.8783 |
| windows 10 1809 (x64) | before 10.0.17763.8276 |
| windows 10 1809 (x86) | before 10.0.17763.8276 |
| windows 10 21h2 | before 10.0.19044.6809 |
| windows 10 22h2 | before 10.0.19045.6809 |
| windows 11 23h2 | before 10.0.22631.6491 |
| windows 11 24h2 | before 10.0.26100.7623 |
| windows 11 25h2 | before 10.0.26200.7623 |
| windows server 2008 (x64) | all listed versions |
| windows server 2008 (x86) | all listed versions |
| windows server 2008 r2 (x64) | all listed versions |
| windows server 2012 | all listed versions |
| windows server 2012 r2 | all listed versions |
| windows server 2016 | before 10.0.14393.8783 |
| windows server 2019 | before 10.0.17763.8276 |
| windows server 2022 | before 10.0.20348.4648 |
| windows server 2022 23h2 | before 10.0.25398.2092 |
| windows server 2025 | before 10.0.26100.32230 |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20869 (Vendor Advisory)
Acknowledgments
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |