Security readout for executives and security teams
Plain-English summary
CVE-2026-26105 is a high-severity SharePoint Server cross-site scripting issue that Microsoft describes as spoofing. An unauthenticated network attacker could influence content shown to a user, but user interaction is required. The main business concern is compromise of user trust and potential exposure or manipulation of sensitive SharePoint data.
Executive priority
Treat this as a high-priority SharePoint patching item, particularly for externally reachable deployments. It is not documented as actively exploited in the provided sources, but the unauthenticated network attack path and high confidentiality and integrity impact justify prompt remediation.
Technical view
The vulnerability is CWE-79: improper neutralization of input during web page generation in Microsoft Office SharePoint. Affected products are SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition, version 16.0.0 as listed. CVSS 3.1 is 8.1 with AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N.
Likely exposure
Organizations running affected on-premises Microsoft SharePoint Server versions may be exposed, especially internet-accessible or broadly accessible portals. The sources do not indicate SharePoint Online impact. Confirm exact product, edition, and update status against Microsoft’s advisory.
Exploitation context
The CVSS data indicates remote network reachability, low attack complexity, no privileges required, and required user interaction. The source bundle marks exploit maturity as unproven and CISA KEV status as false, so there is no sourced evidence here of active exploitation.
Researcher notes
Evidence is limited to the CVE record, CVE List entry, and Microsoft advisory. The description frames the issue as spoofing caused by XSS. No public exploit, proof-of-concept, affected build range beyond listed version data, or detailed remediation instructions are provided in the source bundle.
Mitigation direction
- Review Microsoft’s CVE-2026-26105 advisory for the official security update.
- Prioritize patching internet-facing or high-trust SharePoint deployments.
- Limit external access to SharePoint where business requirements allow.
- Use standard monitoring for suspicious SharePoint page content or user redirection reports.
- If patch timing is delayed, follow any Microsoft-published workarounds or compensating controls.
Validation and detection
- Inventory SharePoint Enterprise Server 2016, 2019, and Subscription Edition deployments.
- Compare installed SharePoint build levels with Microsoft’s advisory.
- Confirm whether affected servers are internet-facing or accessible by untrusted users.
- Verify the Microsoft security update is installed after remediation.
- Review helpdesk and security logs for unusual SharePoint spoofing or XSS reports.
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-2026-26105 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
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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.
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:N/UI:R/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C2.85.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft SharePoint Server Spoofing VulnerabilityCVE reference · 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.