CVE-2025-64401 is a missing authorization vulnerability (CWE-862) found in Apache OpenOffice versions through 4.1.15. The vulnerability arises because documents containing "floating frames" linked to external files automatically load the content of those frames without prompting the user for permission. This lack of authorization checking means that an attacker can craft a malicious OpenOffice document that, when opened, silently loads external resources. Since the vulnerability does not require any privileges or user interaction, it can be exploited remotely by simply convincing a user to open a malicious document. The automatic loading of external content can lead to unauthorized data disclosure or integrity violations, such as leaking internal network information or injecting malicious content into documents. The CVSS v3.1 base score is 7.5 (high), reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to integrity. The vulnerability was publicly disclosed on November 12, 2025, and fixed in Apache OpenOffice version 4.1.16. A similar issue was reported in LibreOffice as CVE-2023-2255, indicating a common underlying problem in open-source office suites. No known exploits are currently reported in the wild, but the ease of exploitation and high impact warrant immediate attention.

For European organizations, this vulnerability poses a significant risk, especially in sectors relying heavily on document exchange such as government, finance, legal, and healthcare. Attackers could exploit this flaw to silently load malicious external content, potentially leading to data leakage, unauthorized data modification, or further compromise of internal networks. Since the vulnerability does not require user interaction or privileges, it increases the risk of widespread exploitation through phishing or targeted document delivery campaigns. The integrity of documents could be compromised, undermining trust in official communications and records. Organizations with strict data protection regulations like GDPR must be particularly cautious, as unauthorized data exposure could result in regulatory penalties and reputational damage. The vulnerability also affects the confidentiality of internal network details if external resources are hosted on internal systems. Although availability is not impacted, the overall security posture and data integrity are at risk.

European organizations should immediately upgrade all Apache OpenOffice installations to version 4.1.16 or later, which contains the patch for CVE-2025-64401. Until upgrades are complete, organizations should implement strict email and document filtering to detect and block suspicious OpenOffice documents containing floating frames or external links. User awareness training should emphasize the risks of opening unsolicited or unexpected documents, even from known contacts. Network-level controls such as restricting outbound HTTP/HTTPS requests from document processing applications can reduce the risk of external content loading. Security teams should monitor for unusual network traffic originating from OpenOffice processes. Additionally, organizations should consider deploying endpoint detection and response (EDR) solutions capable of detecting anomalous document behavior. Reviewing and hardening document handling policies and disabling automatic loading of external content where possible will further reduce exposure.