CVE-2026-33110: Microsoft SharePoint insecure deserialization remote code execution

CVE-2026-33110 · Severity: high · CVSS 8.8 · Published 2026-05-12

Microsoft SharePoint, a widely used platform for document management and team collaboration, contains a security vulnerability that could allow an authorized user to take control of the server. By sending specially crafted data to the system, an attacker with basic user permissions can execute unauthorized commands. This could lead to the theft of sensitive corporate data, disruption of business operations, or a complete compromise of the SharePoint environment.

Technologies: Microsoft SharePoint Server 2016 Enterprise Edition, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition. Vendors: Microsoft.

Quick answers

Is CVE-2026-33110 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-33110 being exploited in the wild.
How severe is CVE-2026-33110?
High severity, with a CVSS score of 8.8, published 12 May 2026.
Which products and versions are affected?
Microsoft SharePoint Server Subscription Edition up to (excluding) 16.0.19725.20280.
Is there a fix for CVE-2026-33110?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-33110 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-33110?
Check whether you run Microsoft SharePoint Server 2016 Enterprise Edition, Microsoft SharePoint Server 2019 or Microsoft SharePoint Server Subscription Edition at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A remote code execution vulnerability exists in Microsoft SharePoint Server due to the insecure deserialization of untrusted data (CWE-502). An attacker must be authenticated to the target environment with at least Site Member permissions to exploit this flaw. By sending a specially crafted network request containing malicious serialized objects, the attacker can trigger arbitrary code execution in the context of the SharePoint service account. The vulnerability affects SharePoint Server 2016, 2019, and Subscription Edition. Microsoft has released security updates to address this issue; users should update SharePoint Server Subscription Edition to version 16.0.19725.20280 or later.

Affected products

  • Microsoft SharePoint Server 2019
  • Microsoft SharePoint Server 2016 Enterprise Edition
  • Microsoft SharePoint Server Subscription Edition up to (excluding) 16.0.19725.20280

Timeline

  • 2026-05-12: disclosed
  • 2026-05-12: advisory: Microsoft published the security update guide.

References

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