CVE-2025-47166 in SharePoint Server
Summary
by MITRE • 06/10/2025
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 • 05/08/2026
This vulnerability represents a critical deserialization flaw that exists within Microsoft Office SharePoint platforms, where the system fails to properly validate or sanitize data received from untrusted sources during the deserialization process. The flaw specifically manifests when SharePoint processes serialized data structures that originate from external or unauthorized sources, creating an opportunity for malicious actors to inject and execute arbitrary code on the affected system. According to the common weakness enumeration framework, this vulnerability maps directly to CWE-502 which describes "Deserialization of Untrusted Data" as a fundamental security weakness that enables attackers to manipulate the deserialization process and gain unauthorized access to system resources.
The technical implementation of this vulnerability allows an attacker who has already established some level of authorization within the SharePoint environment to craft malicious serialized objects that, when processed by the vulnerable system, trigger code execution. This typically occurs through the manipulation of data formats such as xml or binary serialized objects that SharePoint uses for various internal operations and data exchange processes. The attack vector leverages the fact that SharePoint applications often deserialize data from user inputs, web services, or external sources without sufficient validation mechanisms to ensure the integrity and safety of the deserialized content.
Operationally, the impact of this vulnerability extends beyond simple code execution to encompass potential full system compromise and lateral movement within network environments. Once an attacker successfully exploits this vulnerability, they can execute arbitrary commands with the privileges of the SharePoint application pool, potentially allowing them to access sensitive data, modify content, or establish persistence within the environment. The vulnerability's network-based execution capability means that attackers can leverage this flaw from remote locations, making it particularly dangerous in cloud-hosted or internet-facing SharePoint deployments.
Security practitioners should implement multiple layers of defense to mitigate this vulnerability, including strict input validation, disabling unnecessary deserialization capabilities, and implementing proper network segmentation. Organizations should also consider applying Microsoft's security patches and updates promptly while monitoring for suspicious deserialization activities. The attack technique aligns with the tactics described in the attack technique framework where adversaries leverage application vulnerabilities to achieve code execution, specifically targeting the execution phase of the kill chain. Additionally, implementing proper application firewalls and web application firewalls can help detect and prevent malicious deserialization attempts by monitoring for suspicious patterns in serialized data.