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Microsoft, SharePoint
Description
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.
CVSS severity
Critical (9.8/10)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Sourced from NVD, reflects how severe this vulnerability is if exploited, not whether it has been. Every advisory on this page is already a CISA-confirmed active exploitation case regardless of its CVSS score.
EPSS, exploit probability
Critical100.0%
estimated chance of real-world exploitation in the next 30 days, higher than 100.0% of every CVE FIRST.org scores
Refreshed 10/28/2026, via FIRST.org's EPSS model, not CVSS, this measures likelihood of exploitation, not how severe it would be.
Public exploit references (via NVD)
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.
CISA-recommended due date: 2025-07-21
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