CISA KEV · Known exploitedMedium

CVE-2021-31955

Microsoft Windows

CVE-2021-31955 affects Microsoft Windows. Review the CVSS score, exploitation signals, affected versions, remediation status, and linked source material before making a change.

CVSS
5.5
EPSS
81.1%
99.6% percentile
CISA KEV
Listed
Published
2021.06.09
PRIORITY ASSESSMENT

Immediate review

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

Known exploitationConfirmed by CISA KEV
Exploit probability81.1%
Technical severityCVSS 5.5

Vulnerability overview

CVE-2021-31955 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, < 10.0.17763.1999, < 10.0.18363.1621, < 10.0.19041.1052, < 10.0.19042.1052, < 10.0.19043.1052
Fixed versions
10.0.17763.1999, 10.0.18363.1621, 10.0.19041.1052, 10.0.19042.1052, 10.0.19043.1052

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. 1
    Identify

    Confirm that Microsoft Windows and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 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:N/A:N
CWE
CWE-497
KEV added
2021.11.03
Ransomware use
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