CVE-2026-105013 in SharePoint
Summary
by MITRE • 10/13/2026
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability described involves a critical deserialization flaw within the Microsoft Office SharePoint environment, specifically affecting components that process serialized objects from external sources without adequate validation or integrity checks. This class of issue falls under CWE-502, which denotes Deserialization of Untrusted Data, and represents one of the most dangerous categories of application security weaknesses because it allows attackers to manipulate object states during the reconstruction process. In a typical scenario, an attacker who has been authenticated as a legitimate user within the SharePoint infrastructure can craft malicious serialized payloads that exploit unsafe deserialization routines embedded in the server-side processing logic. When these crafted inputs are processed by the vulnerable component, they trigger the instantiation of arbitrary classes or methods with elevated privileges, effectively bypassing standard security controls and leading to remote code execution on the target system.
From an operational perspective, this vulnerability poses a severe risk to organizational integrity because it transforms a routine authentication event into a full compromise vector. An authorized attacker does not need to exploit network-level vulnerabilities such as buffer overflows or injection flaws; instead, they leverage their existing access rights to inject malicious data that the application blindly trusts and executes. This capability aligns with MITRE ATT&CK technique T1059, Command and Scripting Interpreter, specifically when combined with techniques like T1053 Scheduled Task/Job for persistence or T1068 Exploitation for Privilege Escalation if the deserialized code runs under a service account. The impact extends beyond simple data exfiltration; it grants the attacker complete control over the affected server, enabling them to install backdoors, pivot to other systems within the internal network, and potentially escalate privileges to domain administrator levels depending on the context of the SharePoint services running.
Mitigation strategies for this vulnerability require a multi-layered approach focusing on both immediate remediation and long-term architectural hardening. The primary defense is applying the latest security patches provided by Microsoft that address the specific deserialization logic flaws in the affected versions of Office SharePoint Server. Organizations must ensure their patch management processes are agile enough to deploy these updates rapidly, given the high severity associated with remote code execution capabilities. Additionally, implementing strict input validation and allowing only known-safe types during deserialization can prevent exploitation even if a vulnerability exists. Network segmentation plays a crucial role in limiting lateral movement; by restricting access to SharePoint servers from untrusted networks and enforcing least-privilege principles for service accounts, the blast radius of any successful exploit is significantly reduced. Furthermore, enabling advanced logging and monitoring solutions that detect anomalous deserialization patterns or unusual process creations can aid in early detection and incident response efforts.