Security readout for executives and security teams
Plain-English summary
CVE-2025-21393 is a Microsoft SharePoint Server spoofing vulnerability with medium severity. The CVSS data indicates exploitation would require a low-privileged attacker and user interaction, but could expose highly sensitive information and cause limited integrity impact.
Executive priority
Handle this as a routine but time-bound SharePoint patching priority. It is not confirmed as actively exploited in the provided sources, but the confidentiality impact makes delays risky for collaboration environments holding sensitive business data.
Technical view
Microsoft lists affected SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition. The CVE maps to CWE-79 and has CVSS 3.1 score 6.3, with network attack vector, low complexity, low privileges required, user interaction required, high confidentiality impact, and low integrity impact.
Likely exposure
Organizations running the listed Microsoft SharePoint Server products may be exposed if they have not applied the relevant Microsoft security update. Exposure is higher where SharePoint is broadly accessible to users or external partners.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. CVSS marks exploit code maturity as unproven, so treat exploitation status as not confirmed from the provided sources.
Researcher notes
The public data is sparse: Microsoft labels this as spoofing, while the CWE is CWE-79. Validation should focus on affected product presence, patch state, and vendor advisory details rather than assumed exploit mechanics.
Mitigation direction
- Apply Microsoft’s security update guidance for CVE-2025-21393.
- Inventory affected SharePoint Server 2016, 2019, and Subscription Edition systems.
- Prioritize patching internet-facing or widely accessed SharePoint farms.
- If patching is delayed, check Microsoft guidance for supported mitigations.
- Monitor SharePoint activity for unusual user-driven content or access patterns.
Validation and detection
- Confirm deployed SharePoint product and version against Microsoft’s advisory.
- Verify the relevant Microsoft security update is installed on each farm.
- Review vulnerability scanner findings for CVE-2025-21393 coverage.
- Check patch management records for all SharePoint servers.
- Document any unpatched servers and compensating controls.
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-2025-21393 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
- 6.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/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.
SSVC decision data
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:U/C:H/I:L/A:N/E:U/RL:O/RC:C2.14.2microsoftVulnerability scoring details
Base CVSS 3.1 score
6.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N/E:U/RL:O/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft SharePoint Server Spoofing VulnerabilityCVE reference, microsoft · vendor-advisory, patch
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.