CVE-2021-36934
Microsoft Windows 10 1809
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.
Exploitation status
- CISA has confirmed this is being exploited in the wild. That is an observation of real attacks, not a prediction.
- US federal civilian agencies are required to remediate it by 2022-02-24. That deadline does not bind private companies, but it is a reasonable benchmark for how urgently CISA views it.
- A vendor advisory or patch reference has been published.
Required action
Apply updates per vendor instructions.
CISA’s wording, unedited.
What the metrics mean
- It is requires local access to the machine.
- For an attacker who can reach it, no special conditions are needed to exploit it.
- To exploit it, an ordinary user account is needed.
- Beyond that, no action by a user is required.
Scoring
- CVSS
- 7.8 (v3.1)
- Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H- Assigned by
- secure@microsoft.com
Dates
- Published
- 2021-07-22
- Last modified
- 2026-08-10
- Added to KEV
- 2022-02-10
- Remediation due
- 2022-02-24
- Sources
- CISA KEV, NVD
Affected products
- Microsoft Windows 10 1809- 10.0.17763.2114
- Microsoft Windows 10 1909- 10.0.18363.1734
- Microsoft Windows 10 2004- 10.0.19041.1165
- Microsoft Windows 10 20h2- 10.0.19042.1165
- Microsoft Windows 10 21h1- 10.0.19043.1165
As listed in the NVD configuration data. Not a statement about your estate.
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934
- 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