CVE-2021-36934

high

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

https://www.kb.cert.org/vuls/id/506989

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934

http://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html

https://www.tenable.com/cyber-exposure/2021-threat-landscape-retrospective

https://www.welivesecurity.com/wp-content/uploads/2022/02/eset_threat_report_t32021.pdf

https://github.com/DuyDuongDuyDuong/CVE-2021-36934-DLL-Hijacking-DFIR-Investigation

https://github.com/d4yon/CVE-2021-36934-HiveNightmare-Lab

https://github.com/Phemz0/UDMQueries

https://github.com/Phemz0/SocPrimeAreTrash

https://github.com/0xSs0rZ/Windows_Exploit

https://github.com/CnHack3r/Awesome-hacking-tools

https://github.com/chron1k/oxide_hive

https://github.com/shaktavist/SeriousSam

https://github.com/irissentinel/CVE-2021-36934

https://github.com/CrackerCat/HiveNightmare

https://github.com/jmaddington/Serious-Sam---CVE-2021-36934-Mitigation-for-Datto-RMM

https://github.com/bytesizedalex/CVE-2021-36934

https://github.com/tda90/CVE-2021-36934

https://github.com/WiredPulse/Invoke-HiveDreams

https://github.com/romarroca/SeriousSam

https://github.com/n3tsurge/CVE-2021-36934

https://github.com/JoranSlingerland/CVE-2021-36934

https://github.com/HuskyHacks/ShadowSteal

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934

Details

Source: Mitre, NVD

Published: 2021-07-22

Updated: 2026-08-10

Named Vulnerability: SeriouSAMNamed Vulnerability: HiveNightmareKnown Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 4.6

Vector: CVSS2#AV:L/AC:L/Au:N/C:P/I:P/A:P

Severity: Medium

CVSS v3

Base Score: 7.8

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Severity: High

EPSS

EPSS: 0.67252