CVE-2026-99221: keys/trusted_keys: return immediately after TPM unseal failure
CVE-2026-99221 is a vulnerability in keys/trusted_keys: return immediately after TPM unseal failure, rated Low by Microsoft, with a CVSS 3.1 base score of 2.5 (Low). 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. The EPSS model estimates a 0.18% probability of exploitation activity in the next 30 days, higher than 7% of all scored vulnerabilities. Microsoft released the fix on 4 November 2026, outside Patch Tuesday. It affects 1 product in 1 product family (Open Source Software).
Key facts
- CVE ID
- CVE-2026-99221
- Severity
- Low CVSS 2.5
- Microsoft severity
- Low
- Exploited in the wild
- No
- Publicly disclosed
- No
- EPSS
- 0.18% (percentile 7%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- Open Source Software
CVSS score and vector
Microsoft scores CVE-2026-99221 at 2.5 (temporal 2.5) using CVSS 3.1. Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
| Metric | Value |
|---|---|
| Attack vector | Local |
| Attack complexity | High |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | None |
| Integrity impact | Low |
| Availability impact | None |
Affected products (1)
Open Source Software
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 | Release Notes | Security Update |
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |