[ CVE-2025-53770 · Published 20 Jul 2025 ]
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
[ Why it matters ]Priority signals
- Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2025-07-20
- Known to be used in ransomware campaigns
- EPSS: 100% chance of exploitation in the next 30 days (higher than 100% of CVEs)
- Critical severity: CVSS 9.8
[ Description ]Official 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.
CISA: 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.
[ Fixes ]Fixes and patches
CISA required action (US federal deadline 21 Jul 2025): 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.
No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.
[ References ]References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770Vendor Advisory
- arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-u…ExploitPress/Media Coverage
- github.com/kaizensecurity/CVE-2025-53770Exploit
- msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025…MitigationVendor Advisory
- news.ycombinator.com/itemIssue Tracking
- research.eye.security/sharepoint-under-siegeExploitMitigationThird Party Advisory
- therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globallyPress/Media Coverage
- www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-…Press/Media Coverage
- www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sha…Mailing ListThird Party AdvisoryUS Government Resource
- www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoin…Press/Media Coverage
- www.forbes.com/sites/daveywinder/2025/07/20/microsoft-confirms-ongoing-mass-sharepoint-…Press/Media Coverage
- x.com/Shadowserver/status/1946900837306868163Third Party Advisory
- www.cisa.gov/known-exploited-vulnerabilities-catalogUS Government Resource