CVE-2025-53770Known exploitationPublic exploitNetwork attack vector

Unauthenticated code execution via unsafe ToolPane deserialization

Published Jul 20, 2025 · Updated Aug 4, 2026

Unsafe deserialization in Microsoft SharePoint Server 16.0 allows remote attackers to execute arbitrary code through crafted network requests. The ToolPane endpoint processes attacker-controlled serialized data in a crafted POST request, allowing objects that trigger code execution. No account or user interaction is required; successful exploitation runs code in the SharePoint IIS worker process and grants control of the server.

CVSS severity9.8
Critical
EPSS probability100.00%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unsafe deserialization in Microsoft SharePoint Server 16.0 allows remote attackers to execute arbitrary code through crafted network requests. The ToolPane endpoint processes attacker-controlled serialized data in a crafted POST request, allowing objects that trigger code execution. No account or user interaction is required; successful exploitation runs code in the SharePoint IIS worker process and grants control of the server.

The record

CVE
CVE-2025-53770
Published
Jul 20, 2025
Updated
Aug 4, 2026
Vendor
Microsoft
Product
Microsoft SharePoint Enterprise Server 2016
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 18, 2025Exploitation reportedStorm-2603 Warlock ransomware deployment
  2. Jul 20, 2025CVE publishedPublication date reported by the CVE source.
  3. Aug 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=16.0.0 <16.0.5513.1001

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft SharePoint Enterprise Server 2016version=16.0.0 <16.0.5513.1001
Microsoft · Microsoft SharePoint Server 2019version=16.0.0 <16.0.10417.20037
Microsoft · Microsoft SharePoint Server Subscription Editionversion=16.0.0 <16.0.18526.20508

Published CVSS scores

9.8MicrosoftCVSS: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 IPsShadowserver observations through Sep 16, 2026. Gaps indicate unavailable data.
Sep 10, 2026Sep 16, 2026
View daily counts
Reporting dayUnique IPs
Sep 10, 2026Unavailable
Sep 11, 2026Unavailable
Sep 12, 202626
Sep 13, 202619
Sep 14, 2026Unavailable
Sep 15, 2026Unavailable
Sep 16, 2026Unavailable
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

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

Public exploit references

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

Reported exploitation

Technologies

Your stack

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Your stack

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