Security readout for executives and security teams
Plain-English summary
CVE-2020-0891 is a SharePoint reflective cross-site scripting issue. An authenticated attacker could send a crafted request that may run script in a user's browser if the user interacts with it. Business risk is mainly account misuse, data exposure, or content tampering, not server takeover.
Executive priority
Treat this as a moderate-risk SharePoint hygiene issue. It does not indicate known active exploitation in the provided evidence, but exposed legacy SharePoint systems should be checked and remediated through Microsoft guidance.
Technical view
Microsoft describes improper sanitization of a specially crafted request in affected SharePoint servers. The CVSS 3.1 vector is AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N, indicating network reachability, low attack complexity, required authentication, required user interaction, and limited confidentiality and integrity impact.
Likely exposure
Potential exposure applies to Microsoft SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Foundation 2010 SP2 or 2013 SP1. Risk is higher where many internal or external users can authenticate to SharePoint and where vulnerable versions remain in production.
Exploitation context
The provided sources do not establish active exploitation, and the CVE is not marked KEV. Exploitation requires an authenticated attacker and user interaction, consistent with reflective XSS rather than unauthenticated remote code execution.
Researcher notes
Evidence supports CWE-79 reflective XSS with authenticated attacker prerequisites and user interaction. The bundle does not provide exploit details, patch identifiers, or confirmed exploitation, so validation should stay focused on affected product inventory and vendor advisory status.
Mitigation direction
- Review Microsoft's CVE-2020-0891 advisory for applicable vendor guidance and updates.
- Inventory SharePoint versions and prioritize affected systems first.
- Limit SharePoint authentication to trusted users and required access paths.
- Monitor for suspicious SharePoint requests and unusual user-session activity.
Validation and detection
- Confirm whether listed SharePoint products and versions exist in the environment.
- Check patch or advisory status against Microsoft guidance for CVE-2020-0891.
- Validate that SharePoint authentication is limited to intended users.
- Review security logs for abnormal SharePoint request patterns around user sessions.
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-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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-2020-0891 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
- 5.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
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:R/S:C/C:L/I:L/A:N2.32.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.4MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0891CVE 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 Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.