Security readout for executives and security teams
Plain-English summary
This is a high-severity Microsoft SharePoint remote code execution issue. An attacker with a low-privileged SharePoint account could potentially run code on a vulnerable server without user interaction, threatening sensitive data and site integrity.
Executive priority
Treat this as a priority remediation item for any still-supported or legacy SharePoint deployment. The main business risk is authenticated compromise of sensitive collaboration platforms, not confirmed active exploitation.
Technical view
CVE-2021-40487 is a CWE-94 code injection issue in SharePoint Server. CVSS 3.1 is 8.1 with network access, low attack complexity, low privileges required, no user interaction, high confidentiality and integrity impact, and no availability impact listed.
Likely exposure
Exposure is most likely where Microsoft SharePoint Enterprise Server 2016, SharePoint Server 2019, or SharePoint Foundation 2013 SP1 remains deployed and reachable by authenticated users.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The scoring indicates exploitation requires network access and low privileges, not unauthenticated access.
Researcher notes
The bundle provides affected products, CVSS vector, CWE-94 classification, and public advisories. It does not include exploit mechanics, exact fixed builds, or evidence of exploitation, so validation should stay advisory- and scanner-driven.
Mitigation direction
- Review Microsoft’s CVE-2021-40487 advisory for official update guidance.
- Apply applicable Microsoft SharePoint security updates after testing.
- Prioritize internet-facing or broadly accessible SharePoint deployments.
- Restrict SharePoint access to trusted users while remediation is pending.
- Monitor vendor guidance if exact fixed builds are not already tracked internally.
Validation and detection
- Inventory SharePoint versions and map them to the listed affected products.
- Confirm patch status against Microsoft’s CVE-2021-40487 advisory.
- Run authenticated vulnerability scanning after updates are applied.
- Review SharePoint access exposure for low-privileged user paths.
- Check security logs for unusual authenticated SharePoint activity around sensitive sites.
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-2021-40487 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
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C2.85.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/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-2021-40487CVE reference · x_refsource_MISC
- https://www.zerodayinitiative.com/advisories/ZDI-21-1225/CVE 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.