Authenticated content spoofing via undisclosed XSS
Published Jan 13, 2026 · Updated Jan 13, 2026
Cross-site scripting in Microsoft SharePoint Server allows remote authenticated users to spoof rendered content through network input. Microsoft has not disclosed the affected request parameter or rendering path, beyond stating that input is not neutralized during web-page generation. Exploitation requires low-privilege authentication and a victim's interaction; the reported consequence is limited to spoofed content and low data exposure or modification.
Summary
What happened
Cross-site scripting in Microsoft SharePoint Server allows remote authenticated users to spoof rendered content through network input. Microsoft has not disclosed the affected request parameter or rendering path, beyond stating that input is not neutralized during web-page generation. Exploitation requires low-privilege authentication and a victim's interaction; the reported consequence is limited to spoofed content and low data exposure or modification.
The record
- CVE
- CVE-2026-20959
- Published
- Jan 13, 2026
- Updated
- Jan 13, 2026
- Vendor
- Microsoft
- Product
- Microsoft SharePoint Enterprise Server 2016
- Classifications
- CWE-79
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 13, 2026CVE publishedPublication date reported by the CVE source.
- Jan 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=16.0.0 <16.0.5535.1001
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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