CVE-2025-46501 is a Stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the biancardi Mixcloud Embed product up to version 2.2.0. This vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing malicious scripts to be persistently stored and executed in the context of users visiting affected web pages. Specifically, the Mixcloud Embed component, which is used to embed Mixcloud audio content into websites, fails to adequately sanitize or encode input before rendering it in the browser. As a result, an attacker can inject arbitrary JavaScript code that executes whenever a victim accesses the compromised page. This type of vulnerability can lead to session hijacking, credential theft, unauthorized actions on behalf of the user, or distribution of malware. The vulnerability does not require prior authentication or user interaction beyond visiting the affected page, increasing its risk profile. Although no known exploits are currently reported in the wild and no official patches have been released at the time of publication, the presence of this vulnerability in a widely used embedding tool poses a significant risk to web applications and their users. The vulnerability was publicly disclosed on April 24, 2025, and has been enriched with CISA data, indicating recognition by cybersecurity authorities. The lack of a CVSS score necessitates an independent severity assessment based on impact and exploitability factors.

For European organizations, the impact of this Stored XSS vulnerability can be substantial, especially for those relying on Mixcloud Embed to display audio content on their websites or web applications. Exploitation could lead to compromise of user sessions, enabling attackers to impersonate legitimate users, steal sensitive information such as authentication tokens or personal data, and perform unauthorized actions within the victim's session context. This can damage organizational reputation, lead to regulatory non-compliance under GDPR due to data breaches, and cause financial losses. Additionally, attackers could use the vulnerability to distribute malware or conduct phishing attacks by injecting deceptive content. Given the persistent nature of stored XSS, the risk extends to all users accessing the compromised content, potentially amplifying the scope of impact. The vulnerability could also be leveraged as an initial foothold in multi-stage attacks targeting European enterprises, particularly those in media, entertainment, and digital marketing sectors where Mixcloud embeds are more prevalent.

To mitigate this vulnerability effectively, European organizations should: 1) Immediately audit all web properties for the presence of Mixcloud Embed components and identify versions up to 2.2.0 in use. 2) Implement strict Content Security Policy (CSP) headers that restrict script execution sources and disallow inline scripts to reduce the impact of injected scripts. 3) Employ web application firewalls (WAFs) with custom rules to detect and block malicious payloads targeting Mixcloud Embed parameters. 4) Sanitize and encode all user inputs and outputs related to embedded content at the application level, even if relying on third-party components. 5) Monitor web traffic and logs for unusual activity indicative of exploitation attempts. 6) Engage with the vendor or community to obtain patches or updates as soon as they become available and plan for prompt deployment. 7) Educate developers and content managers about the risks of embedding third-party content without proper validation. These steps go beyond generic advice by focusing on immediate detection, containment, and proactive defense tailored to the Mixcloud Embed context.