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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 21 Jul 2025. Known ransomware use
Sharepoint ServerApplication · Microsoft

CVE-2025-53770

CRITICAL · 9.8 CVSS v3.1 Published 2025-07-20
Fix available
A fix is available. Upgrade to 16.0.18526.20508 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized attacker to execute code over a network. Microsoft is aware that an exploit for CVE-2025-53770 exists in the wild. Microsoft is preparing and fully testing a comprehensive update to address this vulnerability. In the meantime, please make sure that the mitigation provided in this CVE documentation is in place so that you are protected from exploitation.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A deserialization vulnerability in on-premises Microsoft SharePoint Server allows unauthenticated remote attackers to execute arbitrary code by sending specially crafted serialized data. This is a critical flaw in how SharePoint processes untrusted data streams.

MitigationApply network segmentation to limit SharePoint server exposure, implement web application firewall rules to detect deserialization attack patterns, and monitor for indicators of compromise until Microsoft's patch is released and deployed.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Sharepoint ServerApplication
Affected:< 16.0.18526.20508= 2016= 2019

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check SharePoint Server version via PowerShell
    Open SharePoint Management Shell and run: (Get-SPFarm).BuildVersion.ToString() or Get-SPFarm | Select-Object BuildVersion
    Affected if Version is less than 16.0.18526.20508, or the version corresponds to SharePoint 2016 or 2019 releases
  2. Verify SharePoint build number in Central Administration
    Navigate to Central Administration > System Settings > Manage farm servers. Note the Version column or check the patch status page showing installed updates and their build numbers
    Affected if Build number falls below 16.0.18526.20508 or matches SharePoint 2016/2019 release builds
  3. Check SharePoint version via registry
    Query the registry key: HKLM\SOFTWARE\Microsoft\Office Server\16.0\Setup\Version or locate the SharePoint version registry entry under the Office Server installation path
    Affected if Registry shows a version string below 16.0.18526.20508, or version identifies as SharePoint 2016 or 2019 (version 16.0.xxxx) without the latest patches applied
  4. Identify network exposure of SharePoint services
    Review firewall rules, load balancer configurations, or network segmentation settings that expose SharePoint sites (port 443/80) to untrusted networks or the internet
    Affected if SharePoint web interfaces are directly accessible from untrusted/external networks without authentication gating or VPN requirements
  5. Check for indicators of compromise
    Review SharePoint logs in Central Administration > Monitoring > Check job status > View diagnostic logs, and examine IIS logs for unusual POST requests to web service endpoints, particularly those involving serialized data patterns
    Affected if Unexpected web service calls, particularly to _vti_bin or API endpoints, with suspicious serialization payloads or anomalous request patterns are found

A SharePoint Server deployment is affected if it runs any version below 16.0.18526.20508, or is SharePoint Server 2016 or 2019, and is exposed to network requests where unauthenticated attackers could send malicious serialized data to SharePoint endpoints.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 16.0.18526.20508 or later
Fixed in 16.0.18526.20508
Interim mitigation

Apply network segmentation to limit SharePoint server exposure, implement web application firewall rules to detect deserialization attack patterns, and monitor for indicators of compromise until Microsoft's patch is released and deployed.

Fix this in Sharepoint Server Exploited in the wild — priority engagement
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
36.0 hours of engineering $6,400
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $10,240.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-53770 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data