Microsoft SharePoint: Elevation of privilege due to missing authorization
Summary
Missing authorization in Microsoft SharePoint Server Subscription Edition (on-premises) allows an authenticated attacker to elevate privileges over the network. The CVSS base score is 8.8 (high) per the vector provided; NVD analysis is still pending. The attacker needs a valid low-privilege account on the farm and no user interaction, and a successful attack would fully compromise confidentiality, integrity and availability. Microsoft's KB5002927 lists the fix in the October 2026 cumulative update.
Affected
- Microsoft SharePoint Server Subscription Edition 16.0.0 to before 16.0.20326.20190 (per CNA record and third-party tracker)
- SharePoint 2016, 2019 and other editions: Unknown.
Fixed in
- Build 16.0.20326.20190 or later, installed via the October 2026 security update (KB5002927)
Workaround
- No CVE-specific workaround found. Unknown.
Exploitation
- No evidence of exploitation found in the sources reviewed.
- No public exploit code found.
- Not listed in CISA KEV according to one tracker.
- Microsoft's exploitability rating: Unknown.
- SharePoint has a history of rapid exploitation (for example ToolShell in 2025), so the rating should not be relied on alone.
Our recommendation
- Install the October 2026 SharePoint security update (build 16.0.20326.20190 or later) and verify the build number on all farm servers.
- Check whether the SharePoint Workflow Manager prerequisite required by KB5002927 is in place.
- Restrict accounts that can authenticate to the farm, and review self-registration, guest access and external sharing.
- Check whether the farm is internet-facing and monitor for unusual privilege changes.
- Confirm the affected builds and exploitability rating on the MSRC page, as the sources could not fully verify them.
- Treat this as high priority.
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)
- KB5002927
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-88176 msrc.microsoft.com
- Microsoft KB5002927: SharePoint security update support.microsoft.com
- OffSeq Radar: CVE-2026-88176 tracker entry radar.offseq.com
- Zero Day Initiative: October 2026 security update review www.zerodayinitiative.com
- Computerworld: October 2026 Patch Tuesday www.computerworld.com
- Cybersecurity Dive: SharePoint attack campaign (ToolShell) www.cybersecuritydive.com
- Vulners: CVE-2026-88176 vulners.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 10 Nov 2026, 20:58.
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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