CVE-2025-53770
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Microsoft SharePoint
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.
Ransomware groups exploiting CVE-2025-53770
The Warlock ransomware and operator(s) are believed to be attributed to Storm-2603, a China-based threat actor who is also known to have deployed LockBit ransomware. There's also a crossover between victims with Black Basta. Both are RaaS and have a long list
Exploitation is attributed to these groups across their recorded activity. It does not follow that every organisation they listed was reached through CVE-2025-53770 — the source data does not record an entry point per incident.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 20 July 2025. US federal agencies were required to remediate it by 21 July 2025. CISA records this vulnerability as known to be used in ransomware campaigns.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 100%, which is higher than 99.9% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Recent listings by these groups
Disclosures from the groups above, newest first.
Frequently asked questions
Is CVE-2025-53770 being exploited by ransomware groups?
Yes. CVE-2025-53770 is recorded as exploited by Warlock. Between them these groups account for 78 victim disclosures in this database. CISA also records this vulnerability as used in ransomware campaigns.
What does CVE-2025-53770 affect?
CVE-2025-53770 affects Microsoft SharePoint. 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 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 100%, higher than 99.9% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 21 July 2025.
How should organisations respond to CVE-2025-53770?
Apply the vendor patch for Microsoft SharePoint as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.