CVE-2023-38177

Authenticated code execution via unsafe gadget deserialization

Published Nov 14, 2023 · Updated Oct 8, 2025

Deserialization in Microsoft SharePoint Server 16.0 allows remote authenticated users to execute code through a crafted site request. SharePoint accepts a serialized Type 4 UnitySerializationHolder gadget and deserializes the untrusted object without restricting dangerous types. Exploitation requires adjacent network access and Site Owner permission to create a site, and the resulting code can read or alter server data.

CVSS severity6.1
Medium
EPSS probability3.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deserialization in Microsoft SharePoint Server 16.0 allows remote authenticated users to execute code through a crafted site request. SharePoint accepts a serialized Type 4 UnitySerializationHolder gadget and deserializes the untrusted object without restricting dangerous types. Exploitation requires adjacent network access and Site Owner permission to create a site, and the resulting code can read or alter server data.

The record

CVE
CVE-2023-38177
Published
Nov 14, 2023
Updated
Oct 8, 2025
Vendor
Microsoft
Product
Microsoft SharePoint Enterprise Server 2016
Classifications
CWE-502, T1190
Attack vector
adjacent
Privileges
admin

Timeline

How it unfolded

  1. Nov 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 8, 2025Record 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 <16.0.5422.1000

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesadmin

What is affected?

Microsoft · Microsoft SharePoint Enterprise Server 2016version=16.0.0 <16.0.5422.1000
Microsoft · Microsoft SharePoint Server 2019version=16.0.0 <16.0.10404.20003
Microsoft · Microsoft SharePoint Server Subscription Editionversion=16.0.0 <16.0.16731.20350

Published CVSS scores

6.1Microsoft CorporationCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
6.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1190Exploit Public-Facing Application

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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