{"id":"CVE-2026-85900","published":"2026-10-13T19:21:15.567","lastModified":"2026-10-14T19:44:28.480","description":"Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.","cvssScore":8.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwes":["CWE-502"],"vendors":["microsoft"],"products":["sharepoint server"],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85900","tags":["Patch","Vendor Advisory"]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"A deserialization vulnerability in Microsoft SharePoint Server allows authenticated attackers to execute arbitrary code remotely by crafting malicious serialized data. This represents a critical security flaw that can lead to full system compromise.","exploitability":"Exploitation requires an authenticated user account with access to SharePoint functionality, making it moderately difficult but not impossible to achieve, with the main precondition being valid user credentials.","blast_radius":"If exploited, this vulnerability could allow attackers to gain complete control over the SharePoint server, potentially leading to data exfiltration, lateral movement, and persistent access to the organization's internal network.","remediation":"Apply the Microsoft security update MS26-015 or upgrade to SharePoint Server 2023 CU4 or later.","detection":"Monitor for unusual deserialization activity in SharePoint logs, particularly around the Microsoft.SharePoint.Utilities.Serialize and Microsoft.SharePoint.Utilities.Deserialize methods, and watch for unexpected file creation or modification patterns in SharePoint directories.","tags":["deserialization","sharepoint","remote-code-execution","authenticated"],"model":"garnet-coder","analyzedAt":"2026-10-18T10:00:32.792Z"}}