CVE-2025-53770
Microsoft SharePoint Deserialization of Untrusted Data
- Published19 Jul 2025
- Added to CISA KEV20 Jul 2025
- Remediation due21 Jul 2025
Description
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.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HAffected products
Remediation
References
- https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-under-exploit-across-the-globe/
- https://github.com/kaizensecurity/CVE-2025-53770
- https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770
- https://news.ycombinator.com/item?id=44629710
- https://research.eye.security/sharepoint-under-siege/
- https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globally
- https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-attacks-no-patch-available/
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53770
- https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770
and 3 more references
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2025-53770 being actively exploited?
Yes. CVE-2025-53770 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 20 Jul 2025. It has been used in ransomware campaigns.
How severe is CVE-2025-53770?
CVE-2025-53770 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 100.0% probability of exploitation.
Which products are affected by CVE-2025-53770?
Affected products include Microsoft SharePoint Server.
How do I fix CVE-2025-53770?
Upgrade affected software to a fixed version, for example Microsoft SharePoint Server 16.0.18526.20508 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2025-53770 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.