CVE-2025-49428 is a medium-severity vulnerability classified under CWE-79, which corresponds to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This vulnerability affects the Dourou Cookie Warning product, specifically versions up to 1.3. The flaw allows an attacker to inject malicious scripts that are stored and later executed in the context of users visiting a website using the vulnerable Cookie Warning plugin. The vulnerability is a Stored XSS, meaning the malicious payload is saved on the server side and delivered to users without proper sanitization or encoding. According to the CVSS 3.1 vector (AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L), the attack can be launched remotely over the network with low attack complexity, but requires high privileges and user interaction. The scope is changed (S:C), indicating that the vulnerability affects resources beyond the initially vulnerable component. The impact includes limited confidentiality, integrity, and availability losses, as the attacker could execute scripts that might steal session tokens, manipulate displayed content, or perform actions on behalf of the user. No known exploits are currently in the wild, and no patches have been linked yet. The vulnerability was published on August 20, 2025, and was reserved in early June 2025. The lack of a patch suggests that affected organizations need to be vigilant and consider mitigation strategies proactively.

For European organizations, the impact of this Stored XSS vulnerability can be significant, especially for those relying on the Dourou Cookie Warning plugin to comply with cookie consent regulations such as the GDPR. Exploitation could lead to unauthorized access to user session data, manipulation of cookie consent dialogs, or redirection to malicious sites, undermining user trust and potentially leading to regulatory penalties. Since cookie consent banners are often displayed on all pages, the attack surface is broad, increasing the risk of widespread impact. The vulnerability could also facilitate phishing or social engineering attacks by injecting deceptive content. Organizations in sectors handling sensitive personal data, such as finance, healthcare, and e-commerce, are particularly at risk. The requirement for high privileges to exploit the vulnerability somewhat limits the attacker's capabilities, but insider threats or compromised administrative accounts could enable exploitation. The change in scope means that the vulnerability could affect other components or services integrated with the Cookie Warning plugin, amplifying the potential damage.

Given the absence of an official patch, European organizations should implement immediate compensating controls. These include: 1) Restricting administrative access to the Dourou Cookie Warning plugin to trusted personnel only and enforcing strong authentication mechanisms such as multi-factor authentication (MFA). 2) Implementing Content Security Policy (CSP) headers to limit the execution of unauthorized scripts and reduce the impact of XSS attacks. 3) Conducting regular code reviews and input validation audits on any customizations related to the Cookie Warning plugin to ensure proper sanitization of user inputs. 4) Monitoring web application logs for unusual activities indicative of attempted XSS exploitation. 5) Considering temporary removal or replacement of the vulnerable plugin with a secure alternative until a patch is released. 6) Educating users and administrators about the risks of XSS and the importance of cautious interaction with web content. 7) Employing Web Application Firewalls (WAFs) configured to detect and block XSS payloads targeting the affected plugin. These measures, combined, can significantly reduce the risk and potential impact of exploitation.