CVE-2026-59126: Windows Event Logging Service Elevation of Privilege Vulnerability
CVE-2026-59126 is an elevation of privilege vulnerability in Windows Event Logging Service, 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 0.20% probability of exploitation activity in the next 30 days, higher than 10% of all scored vulnerabilities. Microsoft released the fix on 11 August 2026 in the August 2026 Patch Tuesday, delivered through 9 security updates (KB5120242, KB5120229, KB5120249, KB5120233 and more). It affects 18 products in 2 product families (Windows, ESU).
Key facts
- CVE ID
- CVE-2026-59126
- 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
- 0.20% (percentile 10%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- August 2026 Patch Tuesday
- Product families
- Windows, ESU
CVSS score and vector
Microsoft scores CVE-2026-59126 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 Event Logging Service 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 (18)
Windows
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows Server 2022 | KB5120242 KB5120229 | Security Update Security Hotpatch Update | 10.0.20348.5499 10.0.20348.5440 | Yes Yes |
| Windows Server 2022 (Server Core installation) | KB5120242 KB5120229 | Security Update Security Hotpatch Update | 10.0.20348.5499 10.0.20348.5440 | Yes Yes |
| Windows 10 Version 21H2 for 32-bit Systems | KB5120249 | Security Update | 10.0.19044.7663 | Yes |
| Windows 10 Version 21H2 for ARM64-based Systems | KB5120249 | Security Update | 10.0.19044.7663 | Yes |
| Windows 10 Version 21H2 for x64-based Systems | KB5120249 | Security Update | 10.0.19044.7663 | Yes |
| Windows Server 2025 (Server Core installation) | KB5120233 KB5120228 | Security Update Security Hotpatch Update | 10.0.26100.33296 10.0.26100.33222 | Yes Yes |
| Windows 11 Version 25H2 for ARM64-based Systems | KB5121003 KB5120994 | Security Update Security Hotpatch Update | 10.0.26200.9168 10.0.26200.9106 | Yes Yes |
| Windows 11 Version 25H2 for x64-based Systems | KB5121003 KB5120994 | Security Update Security Hotpatch Update | 10.0.26200.9168 10.0.26200.9106 | Yes Yes |
| Windows 11 Version 23H2 for ARM64-based Systems | KB5120240 | Security Update | 10.0.22631.7517 | Yes |
| Windows 11 Version 23H2 for x64-based Systems | KB5120240 | Security Update | 10.0.22631.7517 | Yes |
| Windows 11 Version 24H2 for ARM64-based Systems | ||||
| Windows 11 Version 24H2 for x64-based Systems | ||||
| Windows Server 2025 | KB5120233 KB5120228 | Security Update Security Hotpatch Update | 10.0.26100.33296 10.0.26100.33222 | Yes Yes |
| Windows 11 version 26H1 for x64-based Systems | KB5121000 | Security Update | 10.0.28000.2704 | Yes |
| Windows 11 Version 26H1 for ARM64-based Systems | KB5121000 | Security Update | 10.0.28000.2704 | 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 |
Security updates (9)
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 21h2 (arm64) | before 10.0.19044.7663 |
| windows 10 21h2 (x64) | before 10.0.19044.7663 |
| windows 10 21h2 (x86) | before 10.0.19044.7663 |
| windows 10 22h2 (arm64) | before 10.0.19045.7663 |
| windows 10 22h2 (x64) | before 10.0.19045.7663 |
| windows 10 22h2 (x86) | before 10.0.19045.7663 |
| windows 11 23h2 (arm64) | before 10.0.22631.7517 |
| windows 11 23h2 (x64) | before 10.0.22631.7517 |
| windows 11 24h2 (arm64) | before 10.0.26100.9106 |
| windows 11 24h2 (x64) | before 10.0.26100.9106 |
| windows 11 25h2 (arm64) | before 10.0.26200.9106 |
| windows 11 25h2 (x64) | before 10.0.26200.9106 |
| windows 11 26h1 (arm64) | before 10.0.28000.2704 |
| windows 11 26h1 (x64) | before 10.0.28000.2704 |
| windows server 2022 | before 10.0.20348.5440 |
| windows server 2025 (x64) | before 10.0.26100.33222 |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-59126 (Patch, Vendor Advisory)
Acknowledgments
- Anonymous
- yhw
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. | |
| 1.1 | Acknowledgement Updated |