CVE-2025-43827 is an Insecure Direct Object Reference (IDOR) vulnerability classified under CWE-639 (Authorization Bypass Through User-Controlled Key) affecting multiple versions of Liferay Portal and Liferay DXP. Specifically, versions 7.4.0 through 7.4.3.117, and several quarterly releases of Liferay DXP from 2023.Q3.1 through 2024.Q1.5, including older unsupported versions, are impacted. The vulnerability allows remote authenticated users to bypass authorization controls and access audit event data belonging to different virtual instances within the same Liferay deployment. This is achieved by manipulating the _com_liferay_portal_security_audit_web_portlet_AuditPortlet_auditEventId parameter, which is used to reference audit events. Due to insufficient validation of this parameter, an attacker with legitimate access to one virtual instance can view audit logs of other virtual instances, potentially exposing sensitive operational and security-related information. The vulnerability does not require user interaction and can be exploited remotely with low attack complexity, but it does require authenticated access with at least limited privileges (PR:L). The CVSS 4.0 base score is 5.3, indicating a medium severity level, reflecting the moderate impact on confidentiality and low impact on integrity and availability. No known public exploits are reported at this time, and no patches have been linked yet. The issue stems from improper access control checks on audit event identifiers across virtual instances, which undermines the multi-tenancy security model of Liferay Portal and DXP environments.

For European organizations using Liferay Portal or Liferay DXP, this vulnerability poses a risk to confidentiality of audit and security event data across virtual instances. Many enterprises and public sector entities in Europe deploy Liferay for intranet portals, customer engagement platforms, and digital experience management, often leveraging multi-tenant configurations to segregate business units or clients. Unauthorized access to audit logs can reveal sensitive information such as user activities, system changes, and security events, which could be leveraged for further attacks or to gain insights into internal operations. Although the vulnerability does not directly allow system compromise or data modification, the exposure of audit trails can weaken incident response capabilities and compliance with data protection regulations like GDPR. The requirement for authenticated access limits the attack surface to insiders or compromised accounts, but insider threats or credential theft scenarios remain relevant. The absence of known exploits reduces immediate risk, but organizations should consider the potential for future weaponization. Overall, the impact is moderate but significant in environments where audit data confidentiality is critical.

European organizations should implement the following specific mitigations: 1) Immediately review and restrict user permissions to ensure that only authorized personnel have access to audit event data, minimizing the number of accounts with privileges to view audit logs. 2) Monitor and audit access to audit event data for anomalous or cross-virtual instance access patterns that could indicate exploitation attempts. 3) Apply strict network segmentation and access controls between virtual instances to reduce the risk of lateral movement or unauthorized access. 4) Engage with Liferay support or vendor channels to obtain official patches or updates addressing CVE-2025-43827 as soon as they become available, and prioritize their deployment. 5) If patches are not yet available, consider temporary compensating controls such as disabling audit event viewing features for non-administrative users or implementing custom access validation logic where feasible. 6) Conduct internal security awareness training emphasizing the risks of credential compromise and the importance of safeguarding authenticated access. 7) Regularly update and harden authentication mechanisms, including enforcing multi-factor authentication (MFA) for all users with access to Liferay portals. These targeted actions go beyond generic advice by focusing on access control tightening, monitoring, and vendor engagement specific to the nature of this vulnerability.