CISA KEV · Known exploitedHigh

CVE-2021-33771

Microsoft Windows

CVE-2021-33771 affects Microsoft Windows. Review the CVSS score, exploitation signals, affected versions, remediation status, and linked source material before making a change.

CVSS: 7.8
EPSS: 6.25%
CISA KEV: Listed
Published: 2021.07.15

PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV

Exploit probability6.25%

Technical severityCVSS 7.8

Vulnerability overview

CVE-2021-33771 affects Microsoft Windows. Review the CVSS score, exploitation signals, affected versions, remediation status, and linked source material before making a change.

Affected product and versions

Product: Microsoft Windows
Affected versions: 10.0.0, 6.3.0, < 10.0.10240.19003, < 10.0.14393.4530, < 10.0.17763.2061, < 10.0.18363.1679, < 10.0.19041.1110, < 10.0.19042.1110, < 10.0.19043.1110
Fixed versions: 10.0.10240.19003, 10.0.14393.4530, 10.0.17763.2061, 10.0.18363.1679, 10.0.19041.1110, 10.0.19042.1110, 10.0.19043.1110

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

CISA required action

Apply updates per vendor instructions.

Due date: 2021.11.17

1
Identify
Confirm that Microsoft Windows and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE: CWE-119
KEV added: 2021.11.03
Ransomware use: 미확인