Microsoft SharePoint Server Subscription Edition: Cross-site scripting enables spoofing
Summary
A cross-site scripting flaw (CWE-79) in Microsoft SharePoint Server Subscription Edition allows an authorized attacker to perform spoofing over the network. The attacker needs a low-privilege account, and a user must take an action such as opening a crafted page or link. The CVSS vector shows low confidentiality and integrity impact and no availability impact. Microsoft rates the severity as Important, while the CVSS 3.1 base score is 4.6 (Medium).
Affected
- Microsoft SharePoint Server Subscription Edition: 16.0.0 before 16.0.20326.20278
- Other SharePoint versions: Unknown. Verify on the MSRC page.
Fixed in
- Security update KB5002945 (November 2026) for SharePoint Server Subscription Edition, build 16.0.20326.20278 or later
Workaround
Unknown.
Exploitation
- Not known to be exploited.
- No public exploit code known.
- Not listed in the CISA KEV catalog.
- CISA SSVC: exploitation none, automatable no.
Our recommendation
- Install KB5002945 on SharePoint Server Subscription Edition farms, prioritising internet-facing farms.
- Verify that the build is 16.0.20326.20278 or later.
- Check whether your SharePoint estate includes Subscription Edition farms before prioritising.
- Recheck the NVD entry, the MSRC page and the CISA KEV catalog, because NVD analysis was still pending at publication.
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
- CVE Record CVE-2026-109456 www.cve.org
- Microsoft Security Update Guide: CVE-2026-109456 msrc.microsoft.com
- Stefan Gossner blog: SharePoint security fixes November 2026 blog.stefan-gossner.com
- Senserva KB 5002945 senserva.com
- OpenCVE CVE-2026-109456 app.opencve.io
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, 21:06.
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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