CVE-2025-53771
MS Server Products SharePoint Server
Improper authentication in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network.
Ransomware groups exploiting CVE-2025-53771
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-2025-53771 — the source data does not record an entry point per incident.
Exploitation status
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 99.9%, 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:L/I:L/A:N
Recent listings by these groups
Disclosures from the groups above, newest first.
Frequently asked questions
Is CVE-2025-53771 being exploited by ransomware groups?
Yes. CVE-2025-53771 is recorded as exploited by Warlock. Between them these groups account for 78 victim disclosures in this database.
What does CVE-2025-53771 affect?
CVE-2025-53771 affects MS Server Products SharePoint Server. Improper authentication in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network.
How severe is CVE-2025-53771?
CVE-2025-53771 is rated MEDIUM with a CVSS base score of 6.5. EPSS puts the probability of exploitation in the next 30 days at 99.9%, higher than 99.9% of all scored vulnerabilities. It is not currently in the CISA Known Exploited Vulnerabilities catalog.
How should organisations respond to CVE-2025-53771?
Apply the vendor patch for MS Server Products SharePoint Server 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.