Security readout for executives and security teams
Plain-English summary
CVE-2021-40485 is a high-severity Microsoft Excel remote code execution issue. The supplied data indicates a user must interact with a malicious or unsafe file, but successful exploitation could allow code execution with serious confidentiality, integrity, and availability impact.
Executive priority
Treat this as a high-priority patching item, especially for users who receive external documents. The business risk is meaningful because exploitation could lead to full data compromise, but supplied evidence does not support emergency active-exploitation handling.
Technical view
The CVE is classified as CWE-94 with CVSS 3.1 score 7.8, AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Affected products include Excel 2013 SP1, Excel 2016, Office 2019, Office LTSC 2021, Microsoft 365 Apps, Office Online Server, and SharePoint Enterprise Server 2013 SP1.
Likely exposure
Organizations using affected Microsoft Office, Excel, Microsoft 365 Apps, Office Online Server, or listed SharePoint versions may be exposed if security updates are missing.
Exploitation context
The supplied sources do not show active exploitation. CISA KEV is false, and the CVSS exploit maturity is marked unproven. User interaction is required, so risk is most relevant where users open external spreadsheets or Office documents.
Researcher notes
The source bundle gives limited root-cause detail beyond CWE-94 and Microsoft’s RCE classification. Avoid assuming exploit mechanics. Validation should focus on product/version exposure, patch state, and whether affected Office handling paths remain unpatched.
Mitigation direction
- Apply Microsoft’s official update or remediation guidance from the MSRC advisory.
- Prioritize endpoints and servers running listed affected Microsoft Office, Excel, or Office Online products.
- Check vendor guidance before using any workaround not named in Microsoft sources.
- Reduce exposure to untrusted Office documents until affected systems are confirmed patched.
Validation and detection
- Inventory installed Microsoft Office, Excel, Microsoft 365 Apps, Office Online Server, and SharePoint versions.
- Compare inventory against the affected products and versions in the CVE source bundle.
- Verify Microsoft security updates for CVE-2021-40485 are installed where applicable.
- Confirm vulnerability scanner findings are closed after patch deployment.
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.
CWE-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution 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-2021-40485 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
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40485CVE 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.
Improper Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.