Microsoft SharePoint Server: Cross-site scripting enabling spoofing
Summary
A cross-site scripting flaw (CWE-79) in Microsoft SharePoint Server Subscription Edition allows an authenticated attacker to perform spoofing over the network. Exploitation requires a valid low-privilege account and user interaction, such as a victim opening a crafted link or page. The CVSS vector also scores high impact on confidentiality, integrity and availability, which is the conservative view.
Affected
- Microsoft SharePoint Server Subscription Edition, versions 16.0.0 to before 16.0.20326.20278
- On-premises farms only; SharePoint Online in Microsoft 365 is not listed as affected
- SharePoint 2016 and 2019: Unknown
Fixed in
- Build 16.0.20326.20278 or later, included in the November 2026 public update for SharePoint Server Subscription Edition
- Install caveat: farms at the September 2025 CU need a PowerShell script first to correct folder permissions, otherwise the fixes fail to install
Workaround
- Unknown. No mitigation has been identified; apply the update.
Exploitation
- No evidence of exploitation found (third-party view: not in KEV; CISA SSVC: exploitation none, automatable no)
- Public proof of concept: Unknown
Our recommendation
- Confirm the farm is Subscription Edition and check the build against 16.0.20326.20278
- If the farm runs the September 2025 CU, correct folder permissions first as described in the linked guidance, and test before rollout
- Apply the November 2026 update and verify the build afterwards; patch all other SharePoint CVEs in the same update
- Check whether the farm is reachable from the internet and review accounts with access
- Re-check the MSRC advisory and CISA KEV in the coming days, as NVD analysis is still pending
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 Update Guide: CVE-2026-111297 msrc.microsoft.com
- CVE.org CVE Record: CVE-2026-111297 www.cve.org
- Stefan Gossner blog: SharePoint security fixes November 2026 blog.stefan-gossner.com
- Strix: CVE-2026-111297 www.strix.ai
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, 01:57.
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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