A flaw in Microsoft SharePoint Server allows deserialization of untrusted data sent over the network, which an authorized attacker can exploit to execute arbitrary code on the SharePoint host. The vulnerability is an instance of insecure deserialization (CWE-502) and provides the attacker with the ability to run code with the privileges of the SharePoint service, potentially compromising the entire environment.

The affected products are Microsoft SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition. No specific patch level or software version numbers are provided in the advisory, so any installation of these products that has not applied the Microsoft update may be vulnerable.

The CVSS score of 8.8 classifies this exposure as high severity. The EPSS score is 1.147%, indicating a low but nonzero probability of exploitation. The vulnerability was identified by Microsoft and is not listed in the CISA KEV catalog, indicating it has not yet been widely exploited in the field. The likely attack vector requires the attacker to have authenticated or otherwise authorized access to the SharePoint networking layer, and the flaw cannot be triggered solely by arbitrary network traffic.