Security readout for executives and security teams
Plain-English summary
This flaw can let malicious code run through vulnerable Microsoft Office Access Connectivity Engine components after user interaction. Successful exploitation could expose data, alter systems, or disrupt operations. CISA lists the CVE as known exploited, increasing urgency beyond its 7.8 CVSS score.
Executive priority
Treat as a high-priority remediation because exploitation is documented through CISA KEV and successful compromise can affect data and operations. Expedite inventory and patching of affected Office installations, while tracking exceptions until Microsoft guidance confirms they are protected.
Technical view
CVE-2021-38646 is a remote code execution vulnerability affecting listed Microsoft 365 Apps and Office 2013, 2016, and 2019 releases. Its CVSS vector indicates local attack delivery, low complexity, no required privileges, required user interaction, unchanged scope, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely where the listed Office products remain unpatched, especially on user workstations that process untrusted content. The bundle does not identify specific vulnerable components, build ranges, operating systems, or detection indicators, so organizations must confirm applicability through Microsoft’s advisory and their asset inventory.
Exploitation context
CISA KEV inclusion supports that this vulnerability has been exploited in the wild. The supplied evidence does not describe exploitation volume, targeted sectors, campaign attribution, exploit availability, or observed techniques. User interaction is required according to the CVSS vector.
Researcher notes
The bundle provides no CWE, root-cause detail, affected build boundaries, indicators, exploitation telemetry, or specific update identifiers. Avoid inferring the vulnerable parser or delivery format. Use Microsoft’s advisory for authoritative build and patch mapping; use CISA KEV only to substantiate known exploitation.
Mitigation direction
- Apply Microsoft’s security update for CVE-2021-38646 using approved patch-management procedures.
- Prioritize affected user workstations and other systems that process untrusted Office-related content.
- Review Microsoft’s current advisory for product-specific applicability, update details, and any additional mitigations.
- Restrict exposure to untrusted files until affected systems are updated and validated.
Validation and detection
- Inventory installations of the listed Microsoft 365 Apps and Office editions.
- Compare installed builds and update status against Microsoft’s CVE-2021-38646 guidance.
- Confirm security updates installed successfully through endpoint or patch-management reporting.
- Investigate relevant endpoint alerts and suspicious Office-related execution around affected systems.
- Retest update compliance after remediation and document systems requiring exceptions.
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-2021-38646 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: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.
CISA KEV status
SSVC decision data
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:C1.85.9microsoftVulnerability 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
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2021-38646 added to CISA KEV
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2022-03-28T00:00:00.000Z: CVE-2021-38646 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft Office Access Connectivity Engine Remote Code Execution VulnerabilityCVE reference, microsoft · vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-38646CVE reference, CVE · x_refsource_MISC, x_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-38646CVE reference, CISA-ADP · 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.