CVE-2025-51489 is a stored Cross-Site Scripting (XSS) vulnerability affecting MoonShine versions prior to 3.12.5. This vulnerability arises from improper handling of SVG file uploads when creating or updating an Article within the application. Specifically, remote attackers with authenticated access can upload a malicious SVG file containing embedded JavaScript code. When a user subsequently opens the link to this SVG file, the embedded script executes in the context of the victim's browser, leading to arbitrary JavaScript execution. This type of stored XSS is particularly dangerous because the malicious payload is persistently stored on the server and delivered to any user who accesses the compromised content. The vulnerability is classified under CWE-434, which relates to unrestricted file upload vulnerabilities, indicating that the application insufficiently validates or sanitizes uploaded SVG files. The CVSS v3.1 base score is 4.5 (medium severity), with vector AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:N/A:N, meaning the attack can be launched remotely over the network with low attack complexity but requires high privileges (authenticated user) and user interaction (opening the malicious file link). The impact is primarily on confidentiality, as the attacker can execute scripts that may steal sensitive information such as session cookies or perform actions on behalf of the user. There is no indication of known exploits in the wild yet, and no patch links are provided, suggesting that remediation may still be pending or in progress. The vulnerability highlights a critical gap in input validation and content sanitization for SVG uploads in MoonShine CMS, which must be addressed to prevent exploitation.

For European organizations using MoonShine CMS, this vulnerability poses a moderate risk. Attackers with authenticated access—potentially internal users or compromised accounts—can upload malicious SVG files that execute arbitrary JavaScript in the browsers of other users who view the affected articles. This can lead to theft of sensitive information such as authentication tokens, personal data, or internal communications, violating GDPR and other data protection regulations. Although the vulnerability does not directly affect system integrity or availability, the confidentiality breach can have serious compliance and reputational consequences. Organizations with collaborative content management workflows or public-facing content managed via MoonShine are particularly at risk, as attackers may leverage social engineering to induce users to open malicious links. The requirement for authentication and user interaction limits the attack surface but does not eliminate the threat, especially in environments with many users or less stringent access controls. Additionally, the lack of known exploits in the wild suggests an opportunity for proactive mitigation before widespread exploitation occurs.

1. Immediately upgrade MoonShine to version 3.12.5 or later once available, as this version addresses the vulnerability. 2. Until patching is possible, implement strict file upload validation on the server side to restrict SVG uploads or sanitize SVG content to remove embedded scripts. 3. Employ Content Security Policy (CSP) headers to restrict execution of inline scripts and limit the impact of any injected JavaScript. 4. Enforce the principle of least privilege for user accounts, minimizing the number of users with permissions to upload or update articles. 5. Educate users about the risks of clicking on unexpected or suspicious links, especially those pointing to SVG files. 6. Monitor logs for unusual upload activity or access patterns to detect potential exploitation attempts. 7. Consider disabling SVG uploads entirely if not required for business operations. 8. Conduct regular security assessments and code reviews focusing on file upload functionality to prevent similar vulnerabilities.