CVE DATABASE / CVE-2021-36934
CVE-2021-36934
Microsoft Windows SAM Local Privilege Escalation Vulnerability
Confirmed exploited in the wild. Added 2022-02-10.
Federal remediation due 2022-02-24.
Required action: Apply updates per vendor instructions.
Summary
<p>An elevation of privilege vulnerability exists because of overly permissive Access Control Lists (ACLs) on multiple system files, including the Security Accounts Manager (SAM) database. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.</p> <p>An attacker must have the ability to execute code on a victim system to exploit this vulnerability.</p> <p>After installing this security update, you <em>must</em> manually delete all shadow copies of system files, including the SAM database, to fully mitigate this vulnerabilty. <strong>Simply installing this security update will not fully mitigate this vulnerability.</strong> See <a href="https://support.microsoft.com/topic/1ceaa637-aaa3-4b58-a48b-baf72a2fa9e7">KB5005357- Delete Volume Shadow Copies</a>.</p>
CVSS 3.1 breakdown
| Base score | 7.8 (HIGH) |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| Attack vector | LOCAL |
| Attack complexity | LOW |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity | HIGH |
| Availability | HIGH |
Affected products
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References
- http://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934
- https://www.kb.cert.org/vuls/id/506989
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934
Data: NIST NVD + CISA KEV. NVD last modified 2026-02-25. Always verify against the vendor advisory before acting.