May 2026: Microsoft SharePoint Remote Code Execution Vulnerability
CVE-2026-45659 Published on May 22, 2026
Microsoft SharePoint Remote Code Execution Vulnerability
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
Known Exploited Vulnerability
This Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.
The following remediation steps are recommended / required by July 4, 2026: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicab
Weakness Type
What is a Marshaling, Unmarshaling Vulnerability?
The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
CVE-2026-45659 has been classified to as a Marshaling, Unmarshaling vulnerability or weakness.
Products Associated with CVE-2026-45659
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Affected Versions
Microsoft SharePoint Enterprise Server 2016:- Version 16.0.0 and below 16.0.5552.1002 is affected.
- Version 16.0.0 and below 16.0.10417.20128 is affected.
- Version 16.0.0 and below 16.0.19725.20280 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.