Security readout for executives and security teams
Plain-English summary
CVE-2021-31966 is a high-severity remote code execution flaw in Microsoft SharePoint Server. It could let a highly privileged attacker run code on an affected SharePoint server without user interaction. The business risk is serious because SharePoint often stores sensitive documents and supports internal workflows.
Executive priority
Treat this as a high-priority server-side Microsoft patching item. It is not shown as actively exploited in the provided sources, but the impact is severe if a privileged attacker can reach an affected SharePoint deployment.
Technical view
The CVSS 3.1 vector is AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H, scoring 7.2. The issue affects listed SharePoint Server 2013 SP1, 2016, 2019, and SharePoint Foundation 2013 SP1 products. Sources do not provide a CWE or root-cause detail.
Likely exposure
Exposure is most likely in organizations running on-premises Microsoft SharePoint Enterprise Server 2013 SP1, 2016, 2019, or SharePoint Foundation 2013 SP1. Internet-reachable farms and servers used by many privileged administrators should be prioritized.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. The CVSS exploit maturity is unproven, and exploitation requires high privileges, but successful exploitation could affect confidentiality, integrity, and availability.
Researcher notes
Key constraints are high privileges and no user interaction. The bundle lacks CWE, root-cause detail, and exploit specifics. Focus validation on affected on-premises SharePoint inventory, privilege boundaries, build levels, and MSRC remediation status.
Mitigation direction
- Apply Microsoft’s official security guidance for CVE-2021-31966.
- Prioritize affected internet-facing and business-critical SharePoint farms.
- Inventory on-premises SharePoint versions against the affected product list.
- Limit high-privilege SharePoint administrative access to necessary users.
- Review MSRC for version-specific update and deployment requirements.
Validation and detection
- Confirm whether affected SharePoint products and versions are present.
- Verify installed SharePoint build levels against Microsoft guidance.
- Check whether vulnerable farms are internet-accessible or broadly reachable internally.
- Review privileged SharePoint account usage around relevant exposure windows.
- Document patch status for each SharePoint farm and server.
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-2021-31966 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
- 7.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/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:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C1.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.2HighVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/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-2021-31966CVE 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.