# 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.

- Page: https://www.vulneraibility.com/cve/CVE-2021-36934
- CVSS: 7.8
- Known exploited: yes, in CISA KEV since 2022-02-10; CISA due date 2022-02-24
- EPSS: 67.25% (percentile 99.3)
- Unvetted proof-of-concept code on GitHub: 1 Metasploit module · 24 GitHub proofs of concept (first 2021-07-20)
- CISA SSVC: exploitation active, automatable no, technical impact total (assessed 2025-02-04)
- Published: 2021-07-22

## Affected versions

- Microsoft Windows 10 Version 1809: affected >= 10.0.17763.0 and < 10.0.17763.2114; >= 10.0.0 and < 10.0.17763.2114
- Microsoft Windows 10 Version 1909: affected >= 10.0.0 and < 10.0.18363.1734
- Microsoft Windows 10 Version 2004: affected >= 10.0.0 and < 10.0.19041.1165
- Microsoft Windows 10 Version 20H2: affected >= 10.0.0 and < 10.0.19042.1165
- Microsoft Windows 10 Version 21H1: affected >= 10.0.0 and < 10.0.19043.1165

A version outside these ranges is not a statement that it is unaffected.

## References

- [patch] https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934
- [other] https://www.kb.cert.org/vuls/id/506989
- [other] https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934
- [other] http://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934

---
Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.