Microsoft SharePoint Server: Cross-site scripting leading to spoofing
Summary
Microsoft SharePoint Server Subscription Edition (on-premises) contains a cross-site scripting (XSS) vulnerability in its web page generation, classified as CWE-79. An authenticated attacker can inject script that runs in other users' browsers after user interaction, enabling spoofing and possibly exposure of session or data. The CVE record lists only Subscription Edition builds from 16.0.0 up to but not including 16.0.20326.20278; no exploitation or public proof of concept has been found.
Affected
- Microsoft SharePoint Server Subscription Edition (x64, on-premises)
- Builds from 16.0.0 up to but not including 16.0.20326.20278
- SharePoint 2016/2019 and SharePoint Online: unknown, not listed in the CVE record
Fixed in
- Build 16.0.20326.20278 or later (November 2026 CU, reported as KB 5002945; verify on the MSRC page)
Workaround
Unknown. No mitigations were found; check the MSRC page for listed mitigations.
Exploitation
- Exploited in the wild: no evidence found; CISA KEV status not verified
- Public proof of concept: none found
- CISA SSVC: exploitation none, automatable no, technical impact total
Our recommendation
- Check whether you run SharePoint Server Subscription Edition on-premises and identify its build number
- If affected, install the November 2026 CU (KB 5002945) after reviewing the install caveat for farms at the September 2025 CU
- Confirm product scope and mitigations on the MSRC page
- Limit page-editing rights and review user-generated content on internal and extranet sites
- Monitor CISA KEV and MSRC for changes in exploitation status
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Spoofing – Microsoft Office SharePoint
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Microsoft Office
- Updates (KB)
- KB5002945
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Response Center: CVE-2026-111300 msrc.microsoft.com
- CVE Record CVE-2026-111300 www.cve.org
- Stefan Gossner: November 2026 SharePoint security fixes blog.stefan-gossner.com
- Strix.ai: CVE-2026-111300 www.strix.ai
- Rapid7: November 2026 Patch Tuesday www.rapid7.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 06:28.
Original description (NVD)
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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