Authenticated code execution via unsafe deserialization
Published May 12, 2026 · Updated May 12, 2026
Untrusted deserialization in Microsoft SharePoint Server 16.0 allows remote authenticated users to execute code through a network request. Microsoft has not disclosed the affected file, function, serialized payload format, or the operation that accepts the untrusted object data. Exploitation requires authenticated access and user interaction; successful code execution compromises the SharePoint server.
Summary
What happened
Untrusted deserialization in Microsoft SharePoint Server 16.0 allows remote authenticated users to execute code through a network request. Microsoft has not disclosed the affected file, function, serialized payload format, or the operation that accepts the untrusted object data. Exploitation requires authenticated access and user interaction; successful code execution compromises the SharePoint server.
The record
- CVE
- CVE-2026-40368
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- Microsoft
- Product
- Microsoft SharePoint Enterprise Server 2016
- Classifications
- CWE-502, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- May 12, 2026CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=16.0.0 <16.0.5552.1002
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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