CVE-2021-31955
MediumExploitedPublic exploitWindows Kernel Information Disclosure Vulnerability
Published Jun 8, 2021 · Updated Oct 30, 2025
Key Facts
Patch immediately- CVE-2021-31955 is a medium-severity vulnerability (CVSS 5.5 v3.1) affecting Windows 10 1809 (Microsoft), Windows 10 1909 (Microsoft), Windows 10 2004 (Microsoft) and 5 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 14, 2021. Public exploit code is available.
- EPSS estimates a 81% probability of exploitation in the next 30 days.
- Fixed versions are available, including Windows 10 1809 10.0.17763.1999, Windows 10 1809 10.0.18363.1621, Windows 10 1809 10.0.19041.1052.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
5.5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
EPSS (30-day exploit likelihood)
81%
Higher than 99.6% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-31955 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Windows Kernel Information Disclosure Vulnerability
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Not reported |
| Industry KEV feed | Apr 14, 2021 | Nov 17, 2021 | Not reported |
| CIRCL KEV | Nov 3, 2021 | Nov 17, 2021 | Not reported |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
23 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Windows 10 1809Microsoft | 10.0.17763.1999, 10.0.18363.1621, 10.0.19041.1052 | 10.0.17763.1999 |
| Windows 10 1909Microsoft | 10.0.18363.1621 | 10.0.18363.1621 |
| Windows 10 2004Microsoft | See advisory | 10.0.19041.1052 |
| windows 10 20H2Microsoft | 10.0.19042.1052 | 10.0.19042.1052 |
| windows 10 21H1Microsoft | 10.0.19043.1052 | 10.0.19043.1052 |
Patched Releases
Windows 10 1809
10.0.17763.1999, 10.0.18363.1621, 10.0.19041.1052
Windows 10 1909
10.0.18363.1621
Windows 10 2004
10.0.19041.1052
windows 10 20H2
10.0.19042.1052
windows 10 21H1
10.0.19043.1052
Windows Server 2004
10.0.19041.1052
Windows Server 2019
10.0.17763.1999
windows server 20H2
10.0.19042.1052
Timeline
Added to Industry KEV feed
Apr 14, 2021
Publicly disclosed
Jun 8, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Oct 30, 2025
Weakness Type
- CWE-497 Exposure of Sensitive System Information to an Unauthorized Control Sphere
References
FAQ
Common Questions.
Windows Kernel Information Disclosure Vulnerability
Affected: Windows 10 1809 (Microsoft) versions 10.0.17763.1999, 10.0.18363.1621, 10.0.19041.1052; Windows 10 1909 (Microsoft) versions 10.0.18363.1621; Windows 10 2004 (Microsoft), among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 14, 2021.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of Nov 17, 2021.
Public exploit code is available.
Fixed versions are available, including Windows 10 1809 10.0.17763.1999, Windows 10 1809 10.0.18363.1621, Windows 10 1809 10.0.19041.1052.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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