Assessment
Off-by-one error in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to elevate privileges locally.
- Severity
- Important
- CVSS base score
- 5.5
- Impact
- Elevation of Privilege
- Exploitation detected
- No known exploitation (MSRC assessment)
- Exploitability
- Exploitation Less Likely
- Publicly disclosed
- No (MSRC assessment)
- EPSS · 30-day forecast
- No EPSS score collected
- Customer action
- Required: follow the MSRC remediation guidance
More details
- CVSS vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C
- Public detection template
- No Nuclei template is listed in the current collected catalog
- Component
- Windows Container Isolation FS Filter Driver (unionfs.sys)
- Weakness
- CWE-193: Off-by-one Error
- Issued by
- Microsoft
- Last revised
- 10 Nov 2026
CVSS 3.1 base metricsRed raises the risk · green lowers it
- Attack vector
- LocalAV:L
- Attack complexity
- LowAC:L
- Privileges required
- LowPR:L
- User interaction
- NoneUI:N
- Scope
- UnchangedS:U
- Confidentiality
- NoneC:N
- Integrity
- HighI:H
- Availability
- NoneA:N
Updates that fix it
1 KB| KB | Type | Restart | Applies to | Other CVEs |
|---|
| KB5132059 |
Security Update | Required | Windows 11 Version 26H1 for ARM64-based Systems, Windows 11 version 26H1 for x64-based Systems | All CVEs in KB5132059 |
|---|
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