CVE-2021-36934
Microsoft Windows SAM Local Privilege Escalation Vulnerability
CVSS
7.8
High
EPSS
67.3%
p99
KEV
YES
Feb 10, 2022
Exploit Today
80
0-100
Published: Jul 22, 2021 · Last modified: Aug 10, 2026
Product
Microsoft / Windows
Vulnerability
Microsoft Windows SAM Local Privilege Escalation Vulnerability
Added to KEV
Feb 10, 2022
Remediate by
Feb 24, 2022
Known ransomware use
No
Summary description
If a Volume Shadow Copy (VSS) shadow copy of the system drive is available, users can read the SAM file which would allow any user to escalate privileges to SYSTEM level.
Required action
Apply updates per vendor instructions.
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-36934
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. An attacker must have the ability to execute code on a victim system to exploit this vulnerability. After installing this security update, you must manually delete all shadow copies of system files, including the SAM database, to fully mitigate this vulnerabilty. Simply installing this security update will not fully mitigate this vulnerability. See KB5005357- Delete Volume Shadow Copies.
- msrc.microsoft.comhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934
- packetstormsecurity.comhttp://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html
- portal.msrc.microsoft.comhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934
- www.kb.cert.orghttps://www.kb.cert.org/vuls/id/506989
- www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934