CVE-2025-53770
Microsoft SharePoint Server · Collaboration, telephony and video conferencing
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
At a glance
Exploited. Added to CISA’s catalog of exploited vulnerabilities on July 20, 2025.
Used in ransomware attacks, according to CISA.
Affected product: Microsoft SharePoint Server (category Collaboration, telephony and video conferencing, indicative classification). Name in CISA’s catalog: Microsoft SharePoint.
Microsoft component: SharePoint (Messaging and collaboration).
What should I do?
CISA has issued specific instructions for this vulnerability: read the original text and the NVD entry.
Deadline set by CISA for US federal agencies: 1 day (due July 21, 2025). It only binds those agencies, but it is a useful measure of urgency.
- CVE-2025-53770 in Microsoft’s Security Update Guide
- Microsoft security advisories page (general page, not the advisory for this vulnerability)
- The vendor’s specific advisory is listed in the NVD references: CVE-2025-53770 on the NVD website.
Original text of the required action (CISA)
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.
Timeline
- Vulnerability published Publication date (NVD)
- Exploitation confirmed Added to CISA’s KEV catalog
- CISA deadline Remediation deadline set for US federal agencies
The facts, with their sources
- Exploitation confirmed
- Yes, on July 20, 2025 Date added to the catalog of exploited vulnerabilities. Exploitation itself may have started earlier. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- Ransomware
- Known use Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- Hunt for compromise
- Not requested by CISA Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- CISA required action
- CISA has issued specific instructions for this vulnerability: read the original text and the NVD entry. Rewritten by this site from CISA’s original text. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- CISA deadline
- July 21, 2025, 1 day Set for US federal agencies: a measure of urgency, not an obligation elsewhere. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- Microsoft patch
- Not available Source: Security Update Guide, collected September 29, 2026 at 14:57 UTC
- Vulnerability published
- July 20, 2025 Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC
- Product according to CISA
- Microsoft SharePoint Filed by this site under “Collaboration, telephony and video conferencing” (indicative classification). Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Technical detail of the score: attack vector, complexity, impact. Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC
Severity and activity
Score from the vendor or CISA, relayed by the NVD. Collected Sep 29, 2026.
FIRST’s EPSS model. Since exploitation is already confirmed, this figure is mostly useful to compare activity. Collected Sep 29, 2026.
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.
Official description from the NVD, collected Sep 29, 2026. CVE® description © The MITRE Corporation.
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.
Summary from CISA (KEV catalog).
CERT-FR advisories
- CERTFR-2025-ALE-010: [MàJ] Multiples vulnérabilités dans Microsoft SharePoint (updated August 26, 2025)
Information reused under the Open Licence 2.0 (Etalab); the date of last update is shown for each advisory. This site is neither affiliated with nor endorsed by ANSSI.
Sources for this page
- CISA KEV catalog: exploitation, date added, required action, deadline, ransomware.
- Microsoft Security Update Guide: product, patch.
- NVD (NIST): CVSS severity, publication date, description, vendor references.
- EPSS (FIRST): probability of exploitation.
- CERT-FR: advisories and alerts (in French).
- Brand and category: indicative classification by this site (method).