Authenticated code execution via unsafe deserialization
Published Aug 11, 2026 · Updated Aug 25, 2026
Deserialization of untrusted data in Microsoft SharePoint Server allows remote authenticated users to execute code over a network. Microsoft has disclosed the issue only at the product level: SharePoint deserializes attacker-controlled data in an unspecified server-side component, and the vulnerable request path or object sink is not public. Exploitation requires valid low-privilege access to a reachable SharePoint deployment and affects SharePoint Enterprise Server 2016 before 16.0.5565.1001, SharePoint Server 2019 before 16.0.10417.20198, and SharePoint Server Subscription Edition before 16.0.19725.20522.
Summary
What happened
Deserialization of untrusted data in Microsoft SharePoint Server allows remote authenticated users to execute code over a network. Microsoft has disclosed the issue only at the product level: SharePoint deserializes attacker-controlled data in an unspecified server-side component, and the vulnerable request path or object sink is not public. Exploitation requires valid low-privilege access to a reachable SharePoint deployment and affects SharePoint Enterprise Server 2016 before 16.0.5565.1001, SharePoint Server 2019 before 16.0.10417.20198, and SharePoint Server Subscription Edition before 16.0.19725.20522.
The record
- CVE
- CVE-2026-66808
- Published
- Aug 11, 2026
- Updated
- Aug 25, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-502, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 11, 2026CVE publishedPublication date reported by the CVE source.
- Aug 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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