CVEvulnerability
CVE-2025-53770
CISA Known Exploited Vulnerability
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability — Microsoft SharePoint
Microsoft SharePoint Server on-premises contains a deserialization of untrusted data vulnerability that could allow an unauthorized attacker to execute code over a network. This vulnerability could be chained with CVE-2025-53771. CVE-2025-53770 is a patch bypass for CVE-2025-49704, and the updates for CVE-2025-53770 include more robust protection than those for CVE-2025-49704.
- Added to KEV
- 2025-07-20
- Remediation due
- 2025-07-21
- Ransomware use
- Known
- Required action
- Disconnect public-facing versions of SharePoint Server that have reached their end-of-life (EOL) or end-of-service (EOS) to include SharePoint Server 2013 and earlier versions. For supported versions, please follow the mitigations according to CISA (URL listed below in Notes) and vendor instructions (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.
- Notes
- CISA Mitigation Instructions: https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770; https://www.microsoft.com/en-us/security/blog/2025/07/22/disrupting-active-exploitation-of-on-premises-sharepoint-vulnerabilities/ ; https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770 ; https://nvd.nist.gov/vuln/detail/CVE-2025-53770
- Status
- Analyzed
- Published
- 2025-07-20
- Last modified
- 2026-08-04
- Assigner
- [email protected]
- CVSS 3.1 ([email protected])
- 9.8 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weaknesses
- CWE-502
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.
Affected configurations
• microsoft sharepoint server (< 16.0.18526.20508)
• microsoft sharepoint server 2016
• microsoft sharepoint server 2019
Related
Weakness · CWE (1)
- CWE-502 Deserialization of Untrusted Data weakness
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770 Vendor Advisory
- https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-under-exploit-across-the-globe/ Exploit, Press/Media Coverage
- https://github.com/kaizensecurity/CVE-2025-53770 Exploit
- https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/ Mitigation, Vendor Advisory
- https://news.ycombinator.com/item?id=44629710 Issue Tracking
- https://research.eye.security/sharepoint-under-siege/ Exploit, Mitigation, Third Party Advisory
- https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globally Press/Media Coverage
- https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-attacks-no-patch-available/ Press/Media Coverage
- https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770 Mailing List, Third Party Advisory, US Government Resource
- https://www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoint-toolshell-flaw Press/Media Coverage
- https://www.forbes.com/sites/daveywinder/2025/07/20/microsoft-confirms-ongoing-mass-sharepoint-attack---no-patch-available/ Press/Media Coverage
- https://x.com/Shadowserver/status/1946900837306868163 Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53770 US Government Resource