Security readout for executives and security teams
Plain-English summary
CVE-2021-1644 is a high-severity remote code execution flaw in Microsoft HEVC Video Extensions. The CVSS data indicates a user must interact with content, but successful exploitation could allow major confidentiality, integrity, and availability impact.
Executive priority
Treat as a high-priority endpoint remediation item, not an emergency KEV response. Focus on media-handling workstations and broad desktop coverage because successful exploitation could have full system impact.
Technical view
The vulnerability affects Microsoft HEVC Video Extensions. CVSS 3.1 score is 7.8 with local attack vector, low complexity, no privileges required, user interaction required, unchanged scope, and high CIA impact. Official remediation is indicated, but the bundle does not provide implementation details.
Likely exposure
Exposure is likely limited to systems with Microsoft HEVC Video Extensions installed, especially endpoints that open HEVC media from external or untrusted sources. The source bundle does not specify affected versions.
Exploitation context
The bundle marks KEV as false and CVSS exploit maturity as unproven. No cited source in the bundle states active exploitation or public weaponization. User interaction is required according to the CVSS vector.
Researcher notes
Key uncertainty is version detail: the bundle lists affected versions as N/A. Analysis should rely on MSRC records for exact remediation status and any product-specific update channel details.
Mitigation direction
- Review Microsoft MSRC guidance for CVE-2021-1644.
- Apply the official Microsoft-provided remediation for HEVC Video Extensions.
- Prioritize endpoints that process externally sourced HEVC media.
- Limit handling of untrusted HEVC media until remediation is confirmed.
Validation and detection
- Inventory endpoints for Microsoft HEVC Video Extensions installations.
- Check vulnerability scanner findings for CVE-2021-1644.
- Confirm remediation status against Microsoft MSRC guidance.
- Document any systems where affected versions cannot be determined.
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.
Execution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-1644 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:N/UI:R/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:N/UI:R/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:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- HEVC Video Extensions Remote Code Execution VulnerabilityCVE reference · vendor-advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1644CVE 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.