Authenticated code execution via untrusted deserialization
Published May 12, 2026 · Updated May 12, 2026
Untrusted deserialization in Microsoft SharePoint Server allows remote authenticated users to execute code over a network. Microsoft has not disclosed the deserialization locus, serialized object format, or validation operation that accepts attacker-controlled data. A low-privileged authenticated account is required, and successful exploitation runs arbitrary code in the SharePoint Server context.
Summary
What happened
Untrusted deserialization in Microsoft SharePoint Server allows remote authenticated users to execute code over a network. Microsoft has not disclosed the deserialization locus, serialized object format, or validation operation that accepts attacker-controlled data. A low-privileged authenticated account is required, and successful exploitation runs arbitrary code in the SharePoint Server context.
The record
- CVE
- CVE-2026-33112
- 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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