CVE-2024-30043 is a medium-severity vulnerability classified under CWE-611, which pertains to Improper Restriction of XML External Entity (XXE) Reference. This vulnerability affects Microsoft SharePoint Enterprise Server 2016, specifically version 16.0.0. The issue arises from the way SharePoint processes XML input, where external entity references are not properly restricted. This improper handling allows an attacker with at least low-level privileges (PR:L) to craft malicious XML payloads that can be processed by the server without requiring user interaction (UI:N). Exploiting this vulnerability can lead to information disclosure, as the attacker can potentially access sensitive data by leveraging the XXE flaw to read local files or internal resources that are otherwise inaccessible. The CVSS 3.1 base score is 6.5, indicating a medium severity level, with a vector showing network attack vector (AV:N), low attack complexity (AC:L), privileges required (PR:L), no user interaction (UI:N), unchanged scope (S:U), high confidentiality impact (C:H), no integrity or availability impact (I:N/A:N), and an exploit code maturity rated as official (E:U) with remediation level as official fix available (RL:O) and report confidence as confirmed (RC:C). No known exploits are currently reported in the wild. The vulnerability was published on May 14, 2024, and was reserved on March 22, 2024. Given the nature of SharePoint as a widely used enterprise collaboration and document management platform, this vulnerability could expose sensitive organizational data if exploited, particularly in environments where SharePoint is accessible over the network and where users have at least some privileges to submit XML content to the server.

For European organizations, the impact of CVE-2024-30043 could be significant due to the widespread adoption of Microsoft SharePoint Enterprise Server 2016 in various sectors including government, finance, healthcare, and manufacturing. The vulnerability allows an attacker with limited privileges to disclose confidential information without altering system integrity or availability, which could lead to data breaches involving sensitive corporate or personal data protected under GDPR. This could result in regulatory penalties, reputational damage, and loss of trust. Since SharePoint is often integrated with other enterprise systems and contains critical business documents, the exposure of internal files or configuration data could facilitate further attacks or espionage. The medium severity rating reflects that while exploitation requires some privileges, no user interaction is needed, and the attack can be performed remotely, increasing the risk in environments where internal network access is not tightly controlled. Organizations with remote or hybrid work models, where SharePoint access is extended beyond traditional perimeters, may face elevated risks. Additionally, the lack of known exploits in the wild currently provides a window for proactive mitigation before widespread exploitation occurs.

To mitigate CVE-2024-30043, European organizations should prioritize the following actions: 1) Apply any available official patches or updates from Microsoft as soon as they are released, even though no patch links are currently provided, monitoring Microsoft's security advisories closely. 2) Restrict access to SharePoint Enterprise Server 2016 instances to trusted networks and users, employing network segmentation and firewall rules to limit exposure. 3) Implement strict privilege management to ensure that only necessary users have permissions to submit or process XML content within SharePoint, minimizing the attack surface. 4) Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious XML payloads that may contain external entity references. 5) Conduct regular security audits and penetration testing focused on XML processing components to identify and remediate similar weaknesses. 6) Monitor logs for unusual XML processing errors or access patterns that could indicate attempted exploitation. 7) Educate administrators and users about the risks of submitting untrusted XML content and enforce secure coding and configuration practices for any custom SharePoint extensions or integrations that handle XML. These targeted measures go beyond generic advice by focusing on privilege restriction, network controls, and proactive monitoring specific to the nature of the XXE vulnerability in SharePoint.