CVE-2025-43816 is a medium-severity vulnerability identified in the Liferay Portal product, specifically affecting versions 7.4.0 through 7.4.3.119 and multiple versions of Liferay DXP ranging from 2023.Q3.1 through 2024.Q4.10, including unsupported older versions. The vulnerability is classified under CWE-401, which corresponds to a 'Missing Release of Memory after Effective Lifetime,' commonly known as a memory leak. This flaw exists in the headless API for StructuredContents, a component that allows programmatic access to content structures within Liferay Portal. An attacker can exploit this vulnerability by repeatedly invoking the affected API endpoint, causing the server to consume increasing amounts of memory without releasing it. Over time, this leads to resource exhaustion, resulting in server unavailability or denial of service (DoS). The CVSS 4.0 base score is 6.9, indicating a medium severity level, with the vector string showing that the attack requires no privileges (PR:N) but does require user interaction (UI:A), no authentication (AT:N), and has a high impact on availability (VA:H). The vulnerability does not impact confidentiality or integrity. No known exploits are currently reported in the wild, and no official patches are linked yet. The vulnerability affects network-exposed services, making it remotely exploitable over the network without authentication, increasing its risk profile. The root cause is improper memory management in the API's handling of StructuredContents, which fails to free allocated memory after use, leading to gradual memory consumption and eventual service disruption.

For European organizations using Liferay Portal or Liferay DXP, this vulnerability poses a significant risk of service disruption due to denial of service attacks. Liferay Portal is widely used in enterprise content management, intranet portals, and customer-facing websites, including government, education, and private sectors across Europe. A successful exploitation could lead to downtime of critical web services, impacting business continuity, user access, and potentially causing reputational damage. Since the vulnerability requires no authentication, attackers can remotely trigger the memory leak, increasing the attack surface. This is particularly concerning for public-facing portals and APIs exposed to the internet. The lack of confidentiality or integrity impact limits the risk to data breaches, but availability impact alone can cause operational and financial losses. Additionally, organizations with limited capacity for rapid incident response or patch management may experience prolonged outages. The absence of known exploits in the wild provides a window for mitigation, but proactive measures are essential to prevent potential attacks.

European organizations should implement the following specific mitigations: 1) Monitor and limit the rate of API calls to the headless StructuredContents endpoint using web application firewalls (WAFs) or API gateways to prevent abuse through repeated requests. 2) Employ resource usage monitoring and alerting on Liferay Portal servers to detect abnormal memory consumption early. 3) Isolate the Liferay Portal environment in segmented network zones with strict access controls to reduce exposure. 4) Apply any available vendor patches or updates promptly once released; if no patches are available, consider upgrading to unaffected versions or applying vendor-recommended workarounds. 5) Conduct internal penetration testing and fuzzing on the API endpoints to identify and mitigate similar memory management issues proactively. 6) Implement strict user interaction controls and logging to detect suspicious repeated API usage patterns. 7) Engage with Liferay support and subscribe to security advisories for timely updates. These measures go beyond generic advice by focusing on traffic control, monitoring, and network segmentation tailored to the specific API and vulnerability characteristics.