Microsoft SharePoint Server SE: Elevation of privilege
Summary
An elevation of privilege vulnerability (CWE-270, privilege context switching error) affects Microsoft SharePoint Server Subscription Edition. An attacker with a valid low-privilege account can send a specially crafted request to an affected server and perform operations beyond the permissions of that account. Exploitation requires authentication, and no exploitation or public proof of concept is known at publication.
Affected
- Microsoft SharePoint Server Subscription Edition: 16.0.0 to before 16.0.20326.20190 (per the official CVE record; the range is not independently verified)
- SharePoint 2016 and 2019: Unknown.
Fixed in
- Microsoft SharePoint Server Subscription Edition: build 16.0.20326.20190 (KB5002927, October 13, 2026 update)
Workaround
- None documented by the vendor.
- Limit who holds accounts on the farm and review permissions to reduce the impact of an authenticated attacker (general practice, not a vendor recommendation).
Exploitation
- CISA KEV: not listed.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Microsoft Exploit Code Maturity: unproven (E:U).
- Public proof of concept: none found.
- EPSS: unknown.
Our recommendation
- Confirm the installed SharePoint SE build and apply KB5002927 (16.0.20326.20190) or later.
- Before rollout, check the folder permission issue reported on farms at the September 2025 CU level, and test the fix in a non-production environment.
- Verify with the MSRC product list whether SharePoint 2016 or 2019 is affected.
- Review accounts with access to internet-facing sites, including guests and service accounts, and enforce MFA.
- Re-check CISA KEV and the MSRC advisory for changes.
Information from Microsoft (Patch Tuesday October 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)
- KB5002927
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide msrc.microsoft.com
- Microsoft KB5002927 hotfix page support.microsoft.com
- Microsoft SharePoint updates release history learn.microsoft.com
- Stefan Gossner blog: SharePoint security fixes October 2026 blog.stefan-gossner.com
- OpenCVE CVE-2026-88200 app.opencve.io
- VulDB CVE-2026-88200 vuldb.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 31 Oct 2026, 18:01.
Original description (NVD)
Privilege context switching error 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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