Microsoft SharePoint Server: Elevation of privilege due to missing authorization
Summary
Missing authorization in Microsoft SharePoint Server Subscription Edition (on-premises) allows an authorized attacker to elevate privileges over the network. The attack requires high privileges and a complex condition, and no user interaction. Microsoft fixed the flaw in the November 2026 cumulative update (CU); no publicly available exploit code is known.
Affected
- Microsoft SharePoint Server Subscription Edition (on-premises, x64)
- Versions 16.0.0 before 16.0.20326.20278
- SharePoint 2016, SharePoint 2019 and Office Online Server: Unknown.
Fixed in
- Version 16.0.20326.20278 or later
- Patch: KB 5002945, identical with the November 2026 CU for SharePoint Server Subscription Edition
- Farms at the September 2025 CU may need a PowerShell script to correct folder permissions first, otherwise the fixes fail to install. Read the Microsoft blog before patching.
Workaround
Unknown. No workaround is documented in the sources; the patch is the remedy.
Exploitation
- Microsoft rates exploit code maturity as unproven (E:U); no publicly available exploit code is known.
- CISA SSVC: exploitation none, not automatable, total technical impact.
- No CISA KEV entry found in the sources reviewed; recheck the KEV catalog.
Our recommendation
- Install the November 2026 CU on all on-premises SharePoint Subscription Edition servers, after checking the farm's CU level.
- Prioritise internet-facing farms and farms where other SharePoint vulnerabilities are being exploited.
- Review accounts with administrative or high privileges and remove unneeded rights.
- Monitor SharePoint logs for unusual privilege changes until patched.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – 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-2026-109495 msrc.microsoft.com
- CVE Record: CVE-2026-109495 www.cve.org
- Stefan Gossner: SharePoint security fixes with November 2026 PU blog.stefan-gossner.com
- Strix: CVE-2026-109495 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, 11:48.
Original description (NVD)
Missing authorization in Microsoft Office SharePoint allows an authorized attacker to elevate privileges 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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