CVE-2025-59245Network attack vector

Unauthenticated privilege escalation

Published Nov 20, 2025 · Updated Feb 26, 2026

Deserialization of untrusted data in Microsoft SharePoint Online allows remote attackers to elevate privileges via network requests. Microsoft has not published the affected component or the operation that deserializes attacker-controlled data. No authentication or user interaction is required, and elevated access can expose or alter hosted content and interrupt service.

CVSS severity9.8
Critical
EPSS probability1.06%
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 Online allows remote attackers to elevate privileges via network requests. Microsoft has not published the affected component or the operation that deserializes attacker-controlled data. No authentication or user interaction is required, and elevated access can expose or alter hosted content and interrupt service.

The record

CVE
CVE-2025-59245
Published
Nov 20, 2025
Updated
Feb 26, 2026
Vendor
Microsoft
Product
Microsoft SharePoint Online
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 20, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 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=-

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft SharePoint Onlineversion=-

Published CVSS scores

9.8Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
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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