Security readout for executives and security teams
Plain-English summary
CVE-2021-31173 is a Microsoft SharePoint information disclosure issue. A low-privileged user could potentially access sensitive information, but exploitation is rated high complexity. Treat it as a confidentiality risk for SharePoint environments, especially where SharePoint stores regulated, client, or internal business data.
Executive priority
Handle in normal monthly remediation cadence unless the affected SharePoint stores highly sensitive data or is internet-facing. The risk is confidentiality-focused, not service disruption, but SharePoint often contains business-critical documents.
Technical view
The source bundle classifies this as CWE-200 in Microsoft SharePoint with CVSS 3.1 score 5.3. The vector is network-accessible, high complexity, low privileges required, no user interaction, high confidentiality impact, and no integrity or availability impact. The vulnerable component and exposed data are not described.
Likely exposure
Exposure is limited to Microsoft SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Foundation 2013 SP1 as listed in the bundle. Internet-facing SharePoint and environments with many low-privileged users deserve priority review.
Exploitation context
The bundle does not show CISA KEV listing or active exploitation. The CVSS temporal vector records proof-of-concept exploit maturity, but no source here provides exploit details. Do not assume broad exploitation from the supplied evidence.
Researcher notes
Evidence is sparse. The bundle provides affected products, CWE-200, CVSS vector, MSRC reference, and no KEV signal. It does not describe root cause, endpoint, permissions boundary, exact information disclosed, or product-specific KB fixes.
Mitigation direction
- Apply Microsoft guidance and security updates from the MSRC advisory.
- Prioritize externally reachable or sensitive SharePoint deployments.
- Review SharePoint permission hygiene for low-privileged accounts.
- Monitor Microsoft guidance for supersedence or product-specific update details.
Validation and detection
- Inventory SharePoint versions and map them to listed affected products.
- Confirm MSRC-recommended updates are installed on affected servers.
- Review whether vulnerable SharePoint instances are internet-facing.
- Check logs for unusual low-privileged access to sensitive SharePoint content.
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-200: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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 lookupCVE-2021-31173 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
- Medium
- CVSS
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N/E:P/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:N/A:N/E:P/RL:O/RC:C1.63.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N/E:P/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31173CVE 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.
Exposure of Sensitive Information to an Unauthorized Actor
Exposure of Sensitive Information to an Unauthorized Actor represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.