How severe is CVE-2021-31955?

CVE-2021-31955 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-31955 being actively exploited?

Yes. CVE-2021-31955 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2021-31955?

CVE-2021-31955 primarily affects Microsoft Windows 10 1809. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-31955?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2021-31955 have an EU (EUVD) identifier?

Yes. CVE-2021-31955 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-18828. It is also flagged as exploited in the EUVD (since 2021-11-03).

When was CVE-2021-31955 published?

CVE-2021-31955 was published on 2021-06-08 and last updated on 2026-06-17.

CVE-2021-31955

CVE-2021-31955 is a medium-severity vulnerability in Microsoft Windows 10 1809 with a CVSS 3.x base score of 5.5. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2021-11-03). The underlying weakness is classified as CWE-497.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 2.1
EPSS exploit prediction: 81% (100th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2021-11-03)
EU (EUVD) id: EUVD-2021-18828
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2021-11-03)
Weakness: CWE-497
Affected product: Microsoft Windows 10 1809
Published: 2021-06-08
Last modified: 2026-06-17

Description

Windows Kernel Information Disclosure Vulnerability

Frequently asked questions

What is CVE-2021-31955?: Windows Kernel Information Disclosure Vulnerability
How severe is CVE-2021-31955?: CVE-2021-31955 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-31955 being actively exploited?: Yes. CVE-2021-31955 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2021-31955?: CVE-2021-31955 primarily affects Microsoft Windows 10 1809. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31955?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2021-31955 have an EU (EUVD) identifier?: Yes. CVE-2021-31955 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-18828. It is also flagged as exploited in the EUVD (since 2021-11-03).
When was CVE-2021-31955 published?: CVE-2021-31955 was published on 2021-06-08 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2004:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:*

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