Security readout for executives and security teams
Plain-English summary
CVE-2021-31951 is a high-severity Windows Kernel elevation of privilege vulnerability. It matters after an attacker already has low-level local access, because successful exploitation could give them much broader control over the affected Windows system.
Executive priority
Prioritize within normal high-severity Windows patch cycles, faster for domain-connected servers, shared workstations, and systems used by administrators. The main business risk is privilege escalation after initial compromise.
Technical view
The CVSS 3.1 vector is 7.8: local attack vector, low complexity, low privileges required, no user interaction, unchanged scope, and high confidentiality, integrity, and availability impact. Microsoft classifies it as a Windows Kernel elevation of privilege issue with confirmed reporting and official remediation indicated.
Likely exposure
Exposure is most likely on listed Windows 10 and Windows Server builds: Windows 10 1809, 1909, 2004, 20H2, 21H1; Windows Server 2019, Server Core, version 2004, and 20H2.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The CVSS exploit maturity is unproven, so treat this as important privilege-escalation risk, not confirmed in-the-wild exploitation from the supplied evidence.
Researcher notes
The source bundle does not include root-cause detail, affected kernel component internals, exploit primitives, or specific KB numbers. Analysis should remain limited to local EoP exposure, Microsoft affected products, CVSS attributes, and vendor-guided remediation.
Mitigation direction
- Review Microsoft’s advisory for the applicable security update.
- Prioritize patching affected servers and privileged-user workstations.
- Retire or isolate unsupported affected Windows versions where patching is unavailable.
- Limit local logon rights and unnecessary interactive access.
- Monitor Microsoft guidance for any revised remediation details.
Validation and detection
- Inventory endpoints and servers for the listed Windows versions.
- Confirm installed build and update status against Microsoft guidance.
- Check vulnerability scanner findings for CVE-2021-31951.
- Verify high-risk systems received the applicable Microsoft update.
- Review local administrator membership and privileged access paths.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
Privilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-31951 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31951CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.