CVE-2025-46526 is a high-severity reflected Cross-site Scripting (XSS) vulnerability identified in the 'My Custom Widgets' product developed by janekniefeldt, affecting versions up to 2.0.5. This vulnerability arises due to improper neutralization of user input during web page generation, classified under CWE-79. Reflected XSS occurs when malicious scripts are injected into web pages via input parameters and immediately reflected back to the user without proper sanitization or encoding. In this case, an attacker can craft a malicious URL or input that, when visited or submitted by a victim, causes the victim's browser to execute arbitrary JavaScript code. The CVSS 3.1 base score of 7.1 indicates a high severity, with the vector string AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L meaning the attack can be performed remotely over the network with low attack complexity, no privileges required, but requires user interaction (clicking a malicious link). The vulnerability impacts confidentiality, integrity, and availability to a limited extent, as the attacker can potentially steal sensitive information (e.g., session cookies), manipulate the webpage content, or cause denial of service. The scope is changed (S:C), indicating that the vulnerability affects resources beyond the vulnerable component, possibly impacting the entire web application or user session. No known exploits are currently reported in the wild, and no patches or fixes have been linked yet. The vulnerability was reserved in April 2025 and published in May 2025, indicating it is a recent discovery. The affected product, 'My Custom Widgets,' is presumably a web-based widget framework or plugin, which may be used by websites to enhance functionality or user experience.

For European organizations, this vulnerability poses a significant risk, especially for those using the 'My Custom Widgets' product on their websites or web applications. Successful exploitation could lead to session hijacking, unauthorized actions performed on behalf of users, theft of sensitive data such as credentials or personal information, and potential defacement or disruption of services. This can damage organizational reputation, lead to regulatory non-compliance (e.g., GDPR violations due to data leakage), and result in financial losses. The reflected XSS nature means phishing campaigns could be enhanced by embedding malicious links appearing to originate from trusted European websites. Organizations in sectors with high web presence such as e-commerce, finance, healthcare, and government are particularly vulnerable. Additionally, the scope change indicates that the impact could extend beyond the widget itself, potentially compromising the entire web application environment. The lack of known exploits currently provides a window for proactive mitigation before widespread attacks occur.

European organizations should immediately audit their web applications to identify usage of 'My Custom Widgets' versions up to 2.0.5. Since no patches are currently linked, organizations should consider the following mitigations: 1) Implement robust input validation and output encoding on all user-supplied data, especially in areas where the widget processes input. 2) Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS. 3) Use web application firewalls (WAFs) with updated rules to detect and block reflected XSS attack patterns targeting this vulnerability. 4) Educate users and administrators about the risks of clicking suspicious links and encourage safe browsing practices. 5) Monitor web traffic and logs for unusual or suspicious requests that may indicate exploitation attempts. 6) Engage with the vendor or community to obtain patches or updates as soon as they become available and plan for timely deployment. 7) Consider temporary removal or disabling of the vulnerable widget if feasible until a fix is released. These steps go beyond generic advice by focusing on compensating controls and proactive detection tailored to the specific vulnerability context.