Security readout for executives and security teams
Plain-English summary
This is a Windows privilege-escalation flaw in Filter Manager. It is not a remote entry point, but a user or malware already running locally could potentially gain higher control. It affects multiple Windows client and server versions, including legacy systems.
Executive priority
Prioritize remediation in normal high-severity Windows patch cycles, with faster handling for shared or high-value servers. The business risk is privilege escalation after initial access, which can turn a limited compromise into full host control.
Technical view
CVE-2021-31953 is a local Windows Filter Manager elevation-of-privilege vulnerability. CVSS 3.1 is 7.8: local attack vector, low complexity, low privileges required, no user interaction, unchanged scope, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most relevant on affected Windows endpoints and servers from Windows 7/Server 2008 through Windows 10 1809/Server 2019. Systems with local user access, shared workstations, RDS hosts, and servers where untrusted code can run carry higher practical risk.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. CVSS marks exploit maturity as unproven. Treat this as a post-compromise privilege escalation risk, not an internet-facing initial-access vulnerability.
Researcher notes
Public bundle details are sparse: no CWE, no root-cause description, and no exploit narrative are provided. Analysis should stay anchored to MSRC/CVE metadata, CVSS, affected CPEs, and KEV absence unless additional vendor-confirmed data is supplied.
Mitigation direction
- Apply the applicable Microsoft security update for CVE-2021-31953 from MSRC or Windows Update.
- Prioritize shared systems, RDS hosts, and servers where non-admin users can execute code.
- Retire or isolate unsupported legacy Windows versions where normal security updates are unavailable.
- Restrict local logon and code execution rights on high-value Windows servers.
- Monitor Microsoft guidance for any supersedence or servicing-stack prerequisites.
Validation and detection
- Inventory Windows versions and builds against the affected product list in the CVE bundle.
- Confirm applicable Microsoft security updates are installed on each affected host.
- Check vulnerability management results for CVE-2021-31953 after patch deployment.
- Review privileged-access telemetry for unexpected local privilege escalation on affected systems.
- Verify legacy Windows assets have compensating controls if they cannot be patched.
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-2021-31953 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-2021-31953CVE 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.