Security readout for executives and security teams
Plain-English summary
CVE-2021-1647 is a high-severity Microsoft Defender remote code execution issue affecting several Microsoft endpoint protection products. CISA lists it in the Known Exploited Vulnerabilities catalog, so this is not theoretical risk. Organizations should verify affected endpoint protection components received Microsoft’s vendor update.
Executive priority
High priority. KEV status means confirmed exploitation exists, and affected endpoint protection software is broadly deployed. Remediation should be tracked as an exposure-reduction task, not deferred as routine patching.
Technical view
The bundle describes CVE-2021-1647 as Microsoft Defender RCE with CVSS 3.1 score 7.8. The vector shows local access, low complexity, low privileges, no user interaction, and high confidentiality, integrity, and availability impact. Affected products include Windows Defender, Microsoft Security Essentials, and System Center Endpoint Protection variants.
Likely exposure
Exposure is most likely on Windows systems running the listed Microsoft endpoint protection products, especially older, unmanaged, offline, or update-lagging endpoints. The source bundle does not provide exact vulnerable version ranges beyond product-level affected entries.
Exploitation context
Active exploitation is supported by CISA KEV inclusion. The provided sources do not describe observed campaigns, exploit methods, affected version specifics, or indicators of compromise. Treat KEV status as the main urgency signal.
Researcher notes
The source bundle confirms affected product families, CVSS vector, official fix availability, and KEV status, but lacks detailed vulnerable build numbers, root cause, exploit chain, or IOCs. Avoid assuming remote network exploitability from the title alone because the supplied CVSS vector is local.
Mitigation direction
- Apply Microsoft’s vendor update for CVE-2021-1647 using MSRC guidance.
- Confirm endpoint protection components update successfully on all managed systems.
- Prioritize remediation for internet-facing, privileged-user, and high-value workstations.
- Investigate exceptions for offline, legacy, or update-disabled endpoints.
- Monitor CISA KEV requirements and internal remediation deadlines.
Validation and detection
- Inventory systems running the listed Microsoft endpoint protection products.
- Check whether Microsoft’s CVE-2021-1647 update is installed or superseded.
- Review endpoint management reports for failed security component updates.
- Confirm no systems remain on unsupported or unmanaged protection versions.
- Review security telemetry for suspicious activity around affected endpoints.
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-2021-1647 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
- Yes
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/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.
CISA KEV status
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:P/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:P/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft Defender Remote Code Execution VulnerabilityCVE reference · vendor-advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1647CVE reference · x_refsource_MISC, x_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1647CVE reference · government-resource
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.