CVE-2025-43786 is a medium-severity vulnerability classified under CWE-79, which refers to improper neutralization of input during web page generation, commonly known as Cross-site Scripting (XSS). This vulnerability affects multiple versions of the Liferay Portal product, specifically versions 7.4.0 through 7.4.3.128, and various releases of Liferay DXP from 2023.Q4.0 through 2024.Q3.1. The core issue involves the enumeration of ERC (Entity Resource Codes) from object entries within the portal. Attackers can exploit this vulnerability by leveraging timing differences in server responses to determine the existence of specific ERCs within the application. Although the description does not explicitly mention direct XSS exploitation, the CWE-79 classification indicates that the vulnerability arises from insufficient input sanitization during web page generation, which could potentially allow injection of malicious scripts. The CVSS 4.0 score of 6.9 reflects a medium severity with network attack vector, low complexity, no privileges or user interaction required, and limited impact confined to confidentiality. The vulnerability does not affect integrity or availability, and no known exploits are currently in the wild. The lack of available patches at the time of publication suggests that organizations must rely on other mitigation strategies until official fixes are released.

For European organizations using Liferay Portal or Liferay DXP within the affected versions, this vulnerability poses a risk primarily to confidentiality due to the potential for attackers to enumerate internal resource codes. While this may seem limited, such information disclosure can facilitate further targeted attacks, including phishing or social engineering campaigns that exploit knowledge of internal structures. The absence of direct integrity or availability impacts reduces the risk of service disruption or data tampering. However, given Liferay's widespread use in enterprise portals, intranet sites, and customer-facing applications across Europe, exploitation could undermine trust and expose sensitive business information. Organizations operating in regulated sectors such as finance, healthcare, or government may face compliance challenges if sensitive data is indirectly exposed. The vulnerability's network accessibility and lack of required authentication increase the attack surface, making it accessible to remote attackers without credentials. Although no active exploitation is reported, the medium severity and potential for reconnaissance activities warrant proactive attention.

1. Immediate mitigation should include implementing web application firewalls (WAFs) with custom rules to detect and block suspicious timing-based enumeration attempts targeting ERCs. 2. Conduct thorough input validation and output encoding on all user-supplied data, especially in components handling object entries and ERC enumeration, to prevent injection of malicious scripts. 3. Monitor application logs for unusual patterns of requests that could indicate enumeration or probing activities. 4. Restrict access to sensitive portal functionalities by enforcing strict access controls and network segmentation, limiting exposure to trusted networks or VPNs where feasible. 5. Engage with Liferay support channels to obtain patches or updates as soon as they become available and prioritize timely deployment. 6. Perform regular security assessments and penetration testing focused on web application vulnerabilities, including XSS and information disclosure vectors. 7. Educate development and operations teams about secure coding practices related to input sanitization and output encoding to prevent similar vulnerabilities in future releases.