CVE-2026-124226: Microsoft PowerShell Security Feature Bypass Vulnerability
CVE-2026-124226 is a security feature bypass vulnerability in Microsoft PowerShell, rated Important by Microsoft, with a CVSS 3.1 base score of 8.8 (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. Microsoft released the fix on 10 November 2026 in the November 2026 Patch Tuesday, delivered through 8 security updates (KB5131291, KB5131085, KB5131096, KB5131090 and more). It affects 28 products in 2 product families (ESU, Windows).
Key facts
- CVE ID
- CVE-2026-124226
- Severity
- High CVSS 8.8
- Microsoft severity
- Important
- Impact
- Security Feature Bypass
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- Less Likely
- Weakness
- CWE-250
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- ESU, Windows
CVSS score and vector
Microsoft scores CVE-2026-124226 at 8.8 (temporal 7.7) using CVSS 3.1. Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
| Metric | Value |
|---|---|
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Changed |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | High |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Description
Execution with unnecessary privileges in Windows PowerShell allows an authorized attacker to bypass a security feature locally.
Frequently asked questions (Microsoft)
What kind of security feature could be bypassed by successfully exploiting this vulnerability?
An attacker who successfully exploited this vulnerability could bypass Windows Defender Application Control and PowerShell Constrained Language Mode restrictions, allowing untrusted code to run with capabilities those protections are designed to block.
How could an attacker exploit this vulnerability?
An authorized attacker who can execute Windows PowerShell locally under Constrained Language Mode could define and invoke a crafted workflow. Attacker-controlled workflow-definition data is inserted into a generated wrapper that runs in Full Language Mode, allowing the attacker to bypass Windows Defender Application Control and PowerShell Constrained Language Mode restrictions.
Affected products (28)
ESU
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 1607 for 32-bit Systems | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows 10 Version 1607 for x64-based Systems | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows Server 2016 | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows Server 2016 (Server Core installation) | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows 10 Version 22H2 for 32-bit Systems | ||||
| Windows 10 Version 22H2 for x64-based Systems | ||||
| Windows 10 Version 22H2 for ARM64-based Systems |
Windows
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 1809 for 32-bit Systems | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows 10 Version 1809 for x64-based Systems | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows Server 2019 | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows Server 2019 (Server Core installation) | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows 10 Version 21H2 for 32-bit Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows 10 Version 21H2 for x64-based Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows 10 Version 21H2 for ARM64-based Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows Server 2022 | KB5131090 | Security Update | 10.0.20348.5870 | Yes |
| Windows Server 2022 (Server Core installation) | KB5131090 | Security Update | 10.0.20348.5870 | Yes |
| Windows 11 Version 23H2 for x64-based Systems | KB5131087 | Security Update | 10.0.22631.7711 | Yes |
| Windows 11 Version 23H2 for ARM64-based Systems | KB5131087 | Security Update | 10.0.22631.7711 | Yes |
| Windows 11 Version 24H2 for x64-based Systems | KB5135385 | Security Update | 10.0.26100.9968 | Maybe |
| Windows 11 Version 24H2 for ARM64-based Systems | KB5135385 | Security Update | 10.0.26100.9968 | Maybe |
| Windows 11 Version 25H2 for x64-based Systems | ||||
| Windows 11 Version 25H2 for ARM64-based Systems | ||||
| Windows 11 Version 26H2 for x64-based Systems | ||||
| Windows 11 Version 26H2 for ARM64-based Systems | ||||
| Windows Server 2025 | KB5135386 | Security Update | 10.0.26100.33812 | Maybe |
| Windows Server 2025 (Server Core installation) | KB5135386 | Security Update | 10.0.26100.33812 | Maybe |
| Windows 11 version 26H1 for x64-based Systems | KB5132059 | Security Update | 10.0.28000.3501 | Yes |
| Windows 11 Version 26H1 for ARM64-based Systems | KB5132059 | Security Update | 10.0.28000.3501 | Yes |
Security updates (8)
NIST NVD data
- NVD status
- Awaiting Analysis
- NVD CVSS
- 8.8 (HIGH)
- NVD weakness
- CWE-250
- Published to NVD
- NVD last modified
References
Acknowledgments
- Kieran Bloomfield with Microsoft Red Team
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |