CVE-2025-53770

CVE-2025-53770 is a critical-severity vulnerability in Microsoft Sharepoint Server with a CVSS 3.x base score of 9.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2025-07-20). The underlying weakness is classified as CWE-502.

Key facts

• Severity: Critical (CVSS 3.x base score 9.8)
• EPSS exploit prediction: 100% (100th percentile)
• Actively exploited: Yes — listed in CISA KEV (added 2025-07-20)
• EU (EUVD) id: EUVD-2025-23309
• EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2025-07-20)
• Weakness: CWE-502
• Affected product: Microsoft Sharepoint Server
• Published: 2025-07-20
• Last modified: 2026-08-04

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.

Frequently asked questions

What is CVE-2025-53770?

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.

How severe is CVE-2025-53770?

CVE-2025-53770 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-53770 being actively exploited?

Yes. CVE-2025-53770 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2025-07-20, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2025-53770?

CVE-2025-53770 primarily affects Microsoft Sharepoint Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-53770?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2025-53770 have an EU (EUVD) identifier?

Yes. CVE-2025-53770 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-23309. It is also flagged as exploited in the EUVD (since 2025-07-20).

When was CVE-2025-53770 published?

CVE-2025-53770 was published on 2025-07-20 and last updated on 2026-08-04.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770
• 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://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/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770
• https://www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoint-toolshell-flaw
• https://www.forbes.com/sites/daveywinder/2025/07/20/microsoft-confirms-ongoing-mass-sharepoint-attack---no-patch-available/
• https://x.com/Shadowserver/status/1946900837306868163
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53770

Affected products (3)

• cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*
• cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
• cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*

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