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CVE

CVE-2021-33771

Microsoft Windows Kernel Privilege Escalation Vulnerability

Windows Kernel Elevation of Privilege Vulnerability.

HIGH · CVSS 7.8 ⚠ CISA KEV EPSS 0.06523
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS percentile: top 9% of all CVEs by exploitation likelihood
  • CVSS base score ≥ 7.0
Sigma rules10 YARA rules0
⬢

Required Remediation

Apply updates per vendor instructions.

◆

Threat Actors Linked

1
actorCandiru / Sourgum
▤

Affected Products & Versions

15
microsoft windows 10 1507< 10.0.10240.19003
microsoft windows 10 1607< 10.0.14393.4530
microsoft windows 10 1809< 10.0.17763.2061
microsoft windows 10 1909< 10.0.18363.1679
microsoft windows 10 2004< 10.0.19041.1110
microsoft windows 10 20h2< 10.0.19042.1110
microsoft windows 10 21h1< 10.0.19043.1110
microsoft windows 8.1all versions
◈

Sigma Hunt Rules

10
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
relatedcriticalAntivirus Password Dumper Detection
relatedcriticalHacktool Execution - Imphash
relatedcriticalHackTool - Rubeus Execution
relatedcriticalPotential Credential Dumping Via LSASS Process Clone
relatedcriticalWCE wceaux.dll Access
relatedcriticalHackTool - Dumpert Process Dumper Default File
▣

Scoring & Timeline

7.8
HIGH · CVSS v3.1 · secure@microsoft.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD14 Jul 2021 · 06:15 PM
CVSS VectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

2
cisaKEV-CVE-2021-33771
msrcCVE-2021-33771Elevation of Privilege
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33771PatchVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33771US Government Resource
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