CVE-2025-67554 is a stored cross-site scripting (XSS) vulnerability identified in the Humanityco Cookie Notice & Compliance for GDPR / CCPA plugin, specifically affecting all versions up to and including 2.5.8. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, which allows an attacker to inject malicious JavaScript code that is stored persistently on the affected website. When other users visit the compromised pages, the malicious script executes in their browsers within the context of the vulnerable site. This can lead to a range of attacks including session hijacking, credential theft, defacement, or unauthorized actions performed with the victim’s privileges. The plugin is widely used to ensure compliance with privacy regulations such as GDPR and CCPA by managing cookie consent notices. The stored XSS vector is particularly dangerous because it does not require immediate user interaction beyond visiting the infected page, and the malicious payload can affect multiple users over time. No CVSS score has been assigned yet, and no public exploits are known at this time. The vulnerability was published on December 9, 2025, by Patchstack, with no available patches linked yet. The lack of input sanitization or encoding in the plugin’s code responsible for rendering cookie notices is the root cause. This vulnerability highlights the risks inherent in third-party compliance tools that interact with user input and dynamically generate web content.

For European organizations, the impact of this vulnerability can be significant. Since the plugin is designed to manage cookie consent notices to comply with GDPR, any compromise could lead to unauthorized access to user data or session tokens, violating privacy regulations and resulting in heavy fines. The stored XSS can be exploited to steal personal data, manipulate user sessions, or inject fraudulent content, undermining user trust and damaging brand reputation. Organizations operating e-commerce, financial services, or healthcare websites are particularly vulnerable due to the sensitive nature of their data. Additionally, regulatory scrutiny in Europe is stringent, so a breach involving GDPR-related tools can attract severe penalties. The persistence of the XSS payload increases the attack surface and potential number of victims. Furthermore, attackers could leverage this vulnerability to pivot into more extensive attacks within the affected networks. The absence of known exploits currently reduces immediate risk but does not diminish the urgency for mitigation given the ease of exploitation and potential consequences.

European organizations should prioritize the following mitigations: 1) Monitor for and apply security patches from Humanityco immediately once released for this vulnerability. 2) In the interim, restrict or sanitize all user inputs that interact with the cookie notice plugin to prevent injection of malicious scripts. 3) Implement Content Security Policy (CSP) headers to limit the execution of unauthorized scripts on affected pages. 4) Conduct thorough code reviews and penetration testing focusing on input validation and output encoding in all third-party compliance tools. 5) Employ web application firewalls (WAFs) with rules to detect and block XSS payloads targeting the plugin. 6) Educate web developers and administrators about secure coding practices related to dynamic content generation. 7) Regularly audit cookie consent implementations for vulnerabilities and compliance with privacy laws. 8) Consider temporary disabling or replacing the plugin if patches are delayed and risk is high. These steps go beyond generic advice by focusing on immediate containment, layered defenses, and compliance-specific considerations.