CVE-2025-62204 is a deserialization vulnerability classified under CWE-502 affecting Microsoft SharePoint Enterprise Server 2016 version 16.0.0. Deserialization vulnerabilities occur when untrusted data is processed by an application’s deserialization mechanism, potentially allowing attackers to manipulate serialized objects to execute arbitrary code. In this case, an authorized attacker with some level of privilege can send crafted serialized data over the network to the SharePoint server, which improperly deserializes it, leading to remote code execution (RCE). The CVSS v3.1 vector indicates the attack vector is network-based (AV:N), with low attack complexity (AC:L), but requires privileges (PR:L) and user interaction (UI:R). The scope is unchanged (S:U), and the impact is high on confidentiality, integrity, and availability (C:H/I:H/A:H). Although no exploits are currently known in the wild, the vulnerability is critical due to SharePoint’s widespread use in enterprise collaboration and document management. The lack of available patches at the time of publication increases the urgency for mitigation. This vulnerability could allow attackers to compromise sensitive data, disrupt services, or pivot within networks.

For European organizations, the impact of CVE-2025-62204 is significant. Microsoft SharePoint is widely deployed across sectors such as government, finance, healthcare, and manufacturing in Europe, often hosting sensitive documents and enabling critical workflows. Successful exploitation could lead to unauthorized disclosure of confidential information, data tampering, and denial of service. Given that the vulnerability requires some level of privilege and user interaction, insider threats or compromised credentials could be leveraged to exploit it. The potential for remote code execution means attackers could gain persistent footholds, move laterally, and escalate privileges within enterprise networks. This could disrupt business operations, cause regulatory compliance violations (e.g., GDPR breaches), and damage organizational reputation. The absence of known public exploits currently provides a window for proactive defense, but the high CVSS score underscores the urgency to act.

1. Implement the principle of least privilege by restricting user and service account permissions in SharePoint environments to minimize the risk of an attacker having the required privileges. 2. Monitor and audit deserialization-related activities and anomalous network traffic to detect potential exploitation attempts early. 3. Enforce strict input validation and sanitization where possible to reduce the risk of malicious serialized data being processed. 4. Apply network segmentation and firewall rules to limit access to SharePoint servers only to trusted users and systems. 5. Prepare to deploy vendor patches immediately once Microsoft releases them; subscribe to official Microsoft security advisories for updates. 6. Educate users about the risks of interacting with untrusted content or links that could trigger exploitation. 7. Consider deploying application-layer security controls such as Web Application Firewalls (WAFs) with custom rules to detect and block suspicious deserialization payloads. 8. Regularly back up SharePoint data and test restoration procedures to mitigate impact from potential attacks.