Security readout for executives and security teams
Plain-English summary
This is a Microsoft Windows information disclosure issue in the Projected File System filter driver. A local authenticated user could potentially access sensitive information. It is not a remote takeover issue, but exposed systems may leak high-value data if affected Windows builds remain unpatched.
Executive priority
Treat as routine but necessary patch governance. It is not presented as actively exploited or remotely reachable, but confidentiality impact is high, so aging unpatched Windows systems should be remediated in the normal security update cycle.
Technical view
CVE-2021-1663 affects listed Windows 10 and Windows Server 2004/20H2 releases. CVSS 3.1 is 5.5: local attack vector, low complexity, low privileges, no user interaction, high confidentiality impact, and no integrity or availability impact.
Likely exposure
Exposure is most likely on endpoints or servers running the affected Windows 10 Version 2004/20H2 or Windows Server version 2004/20H2 builds. Systems with current Microsoft security updates are less likely to remain exposed.
Exploitation context
The source bundle does not identify active exploitation, and KEV status is false. Exploit maturity is listed as unproven. The attacker position is local with low privileges, which lowers broad internet-facing urgency but still matters for insider or post-compromise scenarios.
Researcher notes
Public detail is limited to an information disclosure in the Windows Projected File System FS filter driver. No CWE, exploit method, or workaround is supplied in the bundle. Avoid assuming broader Windows versions or service configurations beyond the listed affected products.
Mitigation direction
- Apply the Microsoft security update or remediation listed in MSRC guidance.
- Prioritize affected Windows endpoints and servers that handle sensitive data.
- Remove or isolate unsupported affected builds where patching is unavailable.
- Check Microsoft guidance for any product-specific update details.
Validation and detection
- Inventory systems running the affected Windows 10 and Windows Server versions.
- Confirm installed Microsoft security updates against the MSRC advisory.
- Review vulnerability scanner findings for CVE-2021-1663 accuracy.
- Verify no affected build remains in sensitive operational environments.
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.
CVE-2021-1663 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
- Medium
- CVSS
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/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:N/A:N/E:U/RL:O/RC:C1.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- Windows Projected File System FS Filter Driver Information Disclosure VulnerabilityCVE reference · vendor-advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1663CVE reference · x_refsource_MISC, x_transferred
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.