Security readout for executives and security teams
Plain-English summary
CVE-2021-31963 is a Microsoft SharePoint Server remote code execution vulnerability. The listed impact is serious because successful exploitation could compromise sensitive data and allow unauthorized changes. The available evidence does not show active exploitation, and exploitation requires a low-privileged account plus high attack complexity.
Executive priority
Treat this as a high-priority patching and exposure-management item for on-premises SharePoint. It is not supported as an actively exploited emergency from the provided evidence, but impact is high if exploitation succeeds.
Technical view
The CVSS 3.1 vector is AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L, scored 7.1. Affected products are SharePoint Enterprise Server 2013 SP1 and 2016, SharePoint Server 2019, and SharePoint Foundation 2013 SP1. Microsoft lists an official remediation path through its advisory.
Likely exposure
Exposure is most likely in organizations running on-premises Microsoft SharePoint versions listed in the source bundle, especially instances reachable from untrusted networks or many internal users. The bundle does not identify other affected products.
Exploitation context
The source bundle does not support claims of known active exploitation, and KEV status is false. The CVSS vector indicates network reachability, no user interaction, low privileges required, and high attack complexity.
Researcher notes
Evidence is limited to CVE and MSRC metadata. No CWE, root-cause detail, exploit method, or active exploitation source is included. Do not assume unauthenticated exploitation; the provided vector requires low privileges.
Mitigation direction
- Review the Microsoft advisory for the relevant SharePoint product and version.
- Apply the official Microsoft security update or remediation named in the advisory.
- Prioritize internet-facing or broadly accessible SharePoint servers first.
- Restrict SharePoint access to trusted users and networks where feasible.
- Monitor vendor guidance for any revised remediation details.
Validation and detection
- Inventory SharePoint Server and SharePoint Foundation versions in use.
- Confirm whether listed affected versions are present.
- Verify the relevant Microsoft update is installed on each affected server.
- Check vulnerability scanner results for CVE-2021-31963 findings.
- Review access logs for unusual authenticated SharePoint activity.
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-2021-31963 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
- 7.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L/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:H/PR:L/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C1.65.5Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.1HighVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L/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-2021-31963CVE 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.