CVE-2025-43738 is a reflected Cross-Site Scripting (XSS) vulnerability identified in Liferay Portal versions 7.4.0 through 7.4.3.132 and multiple versions of Liferay DXP spanning 2024.Q1.1 through 2025.Q2.8. The vulnerability arises from improper sanitization of user input in the _com_liferay_expando_web_portlet_ExpandoPortlet_displayType parameter. An authenticated remote attacker can inject malicious JavaScript code via this parameter, which is then reflected back in the web application response. This reflected XSS flaw enables attackers to execute arbitrary scripts in the context of the victim's browser session, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the user. The vulnerability requires the attacker to have some level of authenticated access (PR:L - Privileges Required: Low) and user interaction (UI:P - User Interaction: Required), which limits exploitation to some extent. The CVSS 4.0 base score is 5.1, indicating a medium severity level. The attack vector is network-based (AV:N), with low attack complexity (AC:L), and the vulnerability impacts confidentiality and integrity partially (VC:L, VI:L) but not availability. No known exploits are reported in the wild as of the publication date, and no official patches have been linked yet. However, given the widespread use of Liferay Portal and DXP in enterprise web portals, this vulnerability represents a significant risk if exploited.

For European organizations, the impact of this vulnerability can be substantial, especially for those relying on Liferay Portal or DXP for their intranet, customer-facing portals, or digital experience platforms. Exploitation could lead to unauthorized access to sensitive information, session hijacking, and potential lateral movement within corporate networks. This can result in data breaches, loss of user trust, and compliance violations under regulations such as GDPR. Since the vulnerability requires authenticated access, insider threats or compromised user credentials could be leveraged by attackers to exploit this flaw. The reflected XSS could also be used as a vector for delivering further malware or phishing attacks targeting European users. Organizations in sectors such as finance, government, healthcare, and telecommunications, which often use Liferay for their portals, are particularly at risk. The medium severity rating suggests that while the vulnerability is not critical, it still warrants prompt attention to prevent exploitation and mitigate potential reputational and operational damage.

European organizations should implement the following specific mitigation steps: 1) Immediately audit and restrict user privileges to minimize the number of users with authenticated access to the vulnerable parameter. 2) Employ web application firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the _com_liferay_expando_web_portlet_ExpandoPortlet_displayType parameter. 3) Conduct thorough input validation and output encoding on all user-supplied data, particularly focusing on the vulnerable parameter, to prevent script injection. 4) Monitor application logs for unusual activity or repeated attempts to exploit this parameter. 5) Engage with Liferay support or community channels to obtain and apply official patches or updates as soon as they become available. 6) Educate users about phishing and social engineering risks that could lead to credential compromise, which is a prerequisite for exploitation. 7) Consider implementing Content Security Policy (CSP) headers to reduce the impact of any successful XSS attacks by restricting script execution sources. 8) Regularly perform security assessments and penetration testing focused on web application vulnerabilities to detect similar issues proactively.