CVE-2024-38018 is a remote code execution vulnerability identified in Microsoft SharePoint Enterprise Server 2016 (version 16.0.0). The root cause is the deserialization of untrusted data (CWE-502), a common security flaw where maliciously crafted serialized data is processed by the application without proper validation or sanitization. This flaw allows attackers to manipulate the deserialization process to execute arbitrary code remotely on the affected server. The vulnerability requires network access (AV:N), low attack complexity (AC:L), and only low privileges (PR:L) but does not require user interaction (UI:N). The scope is unchanged (S:U), meaning the impact is confined to the vulnerable component. The CVSS v3.1 base score is 8.8, reflecting high confidentiality, integrity, and availability impacts (C:H/I:H/A:H). Although no public exploits are currently known, the vulnerability's nature and severity suggest it could be exploited to gain full control over vulnerable SharePoint servers, leading to data breaches, service disruption, or lateral movement within enterprise networks. The vulnerability was reserved in June 2024 and published in September 2024, with no patches currently linked, indicating organizations must monitor for official updates and advisories.

If exploited, this vulnerability could allow attackers to execute arbitrary code remotely on SharePoint Enterprise Server 2016 systems, leading to full system compromise. This could result in unauthorized access to sensitive corporate data, disruption of collaboration services, and potential lateral movement within enterprise networks. The high impact on confidentiality, integrity, and availability means attackers could steal, modify, or delete critical information and disrupt business operations. Given SharePoint's widespread use in enterprises and government agencies for document management and collaboration, exploitation could have severe operational and reputational consequences. The requirement for only low privileges to exploit increases the risk, as attackers may leverage compromised or low-level accounts to escalate privileges. The absence of user interaction further lowers the barrier for exploitation. Organizations worldwide relying on this SharePoint version face significant risk until mitigations or patches are applied.

Organizations should immediately inventory their SharePoint Enterprise Server 2016 deployments to identify affected systems running version 16.0.0. Until official patches are released, apply the following mitigations: restrict network access to SharePoint servers by implementing strict firewall rules and network segmentation to limit exposure; enforce the principle of least privilege by reviewing and minimizing user permissions, especially for accounts with access to SharePoint; monitor logs and network traffic for unusual deserialization activity or anomalous behavior indicative of exploitation attempts; disable or restrict features that process serialized data if feasible; implement application-layer input validation and sanitization to prevent malicious data from reaching deserialization routines; prepare to deploy patches promptly once available from Microsoft; and consider deploying web application firewalls (WAFs) with custom rules to detect and block exploitation attempts targeting deserialization flaws. Additionally, conduct security awareness training to ensure administrators recognize signs of compromise related to this vulnerability.