CVE-2021-33771Windows Kernel Elevation of Privilege Vulnerability
- 7.8HighCVSS base score
- 10.2%Exploitation in 30 daysEPSS · top 4.3% of all CVEs
- YesKnown exploitedin CISA's KEV since 3 Nov 2021
- YesPublic exploitsa reference or SSVC says so
Description
Windows Kernel Elevation of Privilege Vulnerability
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as Microsoft Windows Kernel Privilege Escalation Vulnerability.
- Added
- 3 Nov 2021
- Fix due (US federal)
- 17 Nov 2021
- Used by ransomware
- Not known
Apply updates per vendor instructions.
ENISA's EU Vulnerability Database lists it as exploited, from CISA's KEV, since 3 Nov 2021.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: it is being exploited.
Timeline
ID reserved
By microsoft
- 47 days later
· 47 days later
Published
- 4 months later
· 4 months later
Added to CISA KEV
Known exploited in the wild
- 5 years later
· 5 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoftCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C |
| NVDNVD · Analyzed | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 10.2% · top 4.3% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
Microsoft · Windows 10 Version 1507
- affected 10.0.10240.0 – < 10.0.10240.19003
Microsoft · Windows 10 Version 1607
- affected 10.0.14393.0 – < 10.0.14393.4530
Microsoft · Windows 10 Version 1809
- affected 10.0.17763.0 – < 10.0.17763.2061
Microsoft · Windows 10 Version 1809
- affected 10.0.0 – < 10.0.17763.2061
Microsoft · Windows 10 Version 1909
- affected 10.0.0 – < 10.0.18363.1679
Microsoft · Windows 10 Version 2004
- affected 10.0.0 – < 10.0.19041.1110
Microsoft · Windows 10 Version 20H2
- affected 10.0.0 – < 10.0.19042.1110
Microsoft · Windows 10 Version 21H1
- affected 10.0.0 – < 10.0.19043.1110
- affected 6.3.0 – < 6.3.9600.20069
Microsoft · Windows Server 2012 R2
- affected 6.3.9600.0 – < 6.3.9600.20069
Microsoft · Windows Server 2012 R2 (Server Core installation)
- affected 6.3.9600.0 – < 6.3.9600.20069
Microsoft · Windows Server 2016
- affected 10.0.14393.0 – < 10.0.14393.4530
Microsoft · Windows Server 2016 (Server Core installation)
- affected 10.0.14393.0 – < 10.0.14393.4530
Microsoft · Windows Server 2019
- affected 10.0.17763.0 – < 10.0.17763.2061
Microsoft · Windows Server 2019 (Server Core installation)
- affected 10.0.17763.0 – < 10.0.17763.2061
Microsoft · Windows Server version 2004
- affected 10.0.0 – < 10.0.19041.1110
Microsoft · Windows Server version 20H2
- affected 10.0.0 – < 10.0.19042.1110
References
References3
- Windows Kernel Elevation of Privilege Vulnerability (opens in a new tab)vendor-advisorypatch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33771 (opens in a new tab)x_refsource_MISCx_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33771 (opens in a new tab)government-resource
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-20448 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-33771)Record last updated .