Microsoft SharePoint Server SE: Elevation of privilege (SSRF)
Summary
A server-side request forgery (SSRF) vulnerability in on-premises Microsoft SharePoint Server Subscription Edition allows an authorized attacker to elevate privileges over the network. The CVSS vector rates confidentiality, integrity and availability impact as high. The sources do not explain how the flaw works, so the exact attack path is unclear.
Affected
- Microsoft SharePoint Server Subscription Edition (on-premises): 16.0.0 before 16.0.20326.20278
- Other SharePoint versions: not confirmed by the sources; check the MSRC advisory
Fixed in
- Build 16.0.20326.20278 or later
- Fix: November 2026 SharePoint Server Subscription Edition update (KB 5002945), according to a third-party blog; verify on MSRC
Workaround
- No vendor-published workaround found. Unknown whether one exists.
- Installation note: if the farm is at the September 2025 CU level, run the folder-permission script first, or the fixes fail to install.
Exploitation
- No evidence of exploitation in the wild found. Not listed in CISA KEV according to the aggregator Strix; unverified.
- No public proof of concept found. Unknown.
- Attack requires network access and a valid low-privilege account, but no user interaction.
Our recommendation
- If you run on-premises SharePoint Server Subscription Edition, treat this as high priority.
- Confirm the build number and apply the November 2026 update or a build 16.0.20326.20278 or later.
- Check the September 2025 CU script requirement before installing.
- Review accounts that can reach the SharePoint server and remove unneeded access.
- Check whether the server is internet-facing; if so, act first.
- Verify the affected-version list on MSRC and monitor CISA KEV and NVD once analysed.
- If you use only SharePoint Online (Microsoft 365) or SharePoint 2019/2016, verify on MSRC whether this CVE applies.
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-2026-109502 msrc.microsoft.com
- CVE Record: CVE-2026-109502 www.cve.org
- Stefan Gossner: SharePoint security fixes released with November 2026 PU blog.stefan-gossner.com
- Strix: CVE-2026-109502 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 10 Nov 2026, 23:52.
Original description (NVD)
Server-side request forgery (ssrf) 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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