CVE-2025-49712: Deserialization of Untrusted Data in Microsoft Office SharePoint

Overview

In the realm of cybersecurity, vulnerabilities refer to weaknesses that could potentially be exploited by malevolent actors to compromise a system. One such vulnerability, identified as CVE-2025-49712, has been recently detected in Microsoft Office SharePoint. This vulnerability is particularly dangerous because it allows an authorized attacker to execute code over a network.
Microsoft Office SharePoint is a widely used platform for collaboration and document management, which signifies the severity of this vulnerability. The potential fallout from a successful exploit includes system compromise and data leakage, which could be devastating for businesses that use SharePoint for storing and sharing sensitive information.

Vulnerability Summary

CVE ID: CVE-2025-49712
Severity: High (8.8 on CVSS Severity Score)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: System compromise or data leakage

Affected Products

Product | Affected Versions

Microsoft Office SharePoint | All versions prior to the latest patch

How the Exploit Works

The vulnerability stems from the deserialization of untrusted data in Microsoft Office SharePoint. Deserialization is the process of converting a stream of bytes back into a copy of the original object. When an attacker can manipulate the serialized data and it’s deserialized without validation, it can lead to malicious code execution.
In this case, an attacker who is already authenticated on the SharePoint server can send a specially crafted payload that, when deserialized by the SharePoint server, leads to the execution of arbitrary code. This could allow the attacker to take control of the server, potentially gaining access to sensitive information or disrupting services.

Conceptual Example Code

This is a conceptual example of how the vulnerability might be exploited. This example uses a malicious JSON payload in a POST request to a vulnerable SharePoint endpoint.

POST /vulnerable/endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/json
{
"malicious_payload": "{ serialized_object_with_malicious_code }"
}

Upon receiving this request, the SharePoint server would then deserialize the payload, executing the malicious code embedded within it.

Mitigation Guidance

The most effective way to mitigate this vulnerability is to apply the patch provided by the vendor, Microsoft, as soon as it becomes available. Until then, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) could be used to detect and block attempts to exploit this vulnerability. Regular monitoring and auditing of SharePoint servers for any unusual activity is also recommended.