CVE-2026-33110Network attack vector

Authenticated code execution via untrusted deserialization

Published May 12, 2026 · Updated May 12, 2026

Deserialization of untrusted data in Microsoft SharePoint Server allows remote authenticated users to execute code over a network. Microsoft identifies unsafe deserialization as the faulty operation but does not disclose the affected component, endpoint, or serialized input format. A low-privileged account and network access are sufficient; successful exploitation can compromise the server's confidentiality, integrity, and availability.

CVSS severity8.8
High
EPSS probability1.97%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deserialization of untrusted data in Microsoft SharePoint Server allows remote authenticated users to execute code over a network. Microsoft identifies unsafe deserialization as the faulty operation but does not disclose the affected component, endpoint, or serialized input format. A low-privileged account and network access are sufficient; successful exploitation can compromise the server's confidentiality, integrity, and availability.

The record

CVE
CVE-2026-33110
Published
May 12, 2026
Updated
May 12, 2026
Vendor
Microsoft
Product
Microsoft SharePoint Enterprise Server 2016
Classifications
CWE-502, T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=16.0.0 <16.0.5552.1002

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft SharePoint Enterprise Server 2016version=16.0.0 <16.0.5552.1002
Microsoft · Microsoft SharePoint Server 2019version=16.0.0 <16.0.10417.20128
Microsoft · Microsoft SharePoint Server Subscription Editionversion=16.0.0 <16.0.19725.20280

Published CVSS scores

8.8Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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