CVE-2021-36934
Microsoft Windows 10 Version 1809, Microsoft Windows 10 Version 1909, Microsoft Windows 10 Version 2004
Published 22 Jul 2021 · updated 10 Aug 2026 · Analyzed
Exploited in the wild
CISA added this to its Known Exploited Vulnerabilities catalog on 10 Feb 2022, with a remediation deadline of 24 Feb 2022 for US federal agencies.
Required action: Apply updates per vendor instructions.
Description
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.
References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934 · Patch, Vendor Advisory
- packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html · Third Party Advisory, VDB Entry
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934 · Patch, Vendor Advisory
- www.kb.cert.org/vuls/id/506989 · Third Party Advisory
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934 · US Government Resource