CVE-2025-51487 is a stored Cross-Site Scripting (XSS) vulnerability identified in MoonShine versions prior to 3.12.5. This vulnerability arises from improper validation of the CutCode Link parameter when creating or updating an Article within the application. Specifically, the application expects this parameter to contain URLs with the HTTPS protocol; however, it fails to properly sanitize inputs that use the "javascript:" URI scheme. An attacker can exploit this flaw by injecting arbitrary JavaScript code via the CutCode Link parameter, which is then stored persistently on the server and rendered in the context of users viewing the affected article. When a victim accesses the compromised article, the malicious script executes in their browser under the trust domain of the MoonShine application. This can lead to theft of sensitive information such as session cookies, user impersonation, or execution of unauthorized actions on behalf of the user. The vulnerability is classified under CWE-79, indicating a classic XSS issue. The CVSS v3.1 base score is 4.5, reflecting a medium severity level, with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), requiring high privileges (PR:H), and user interaction (UI:R). The impact is primarily on confidentiality (C:H), with no direct integrity or availability impact. No known exploits are reported in the wild as of now, and no official patches or mitigation links have been provided yet. The vulnerability was published on August 19, 2025, with the reservation date on June 16, 2025.

For European organizations using MoonShine versions prior to 3.12.5, this vulnerability poses a risk of client-side script injection leading to potential data leakage and session hijacking. Since the exploit requires high privileges to create or update articles, the threat is more significant in environments where multiple users have content management access, such as media companies, publishing platforms, or internal knowledge bases. The stored nature of the XSS means that once injected, all users viewing the affected content are at risk, potentially leading to widespread compromise of user accounts or unauthorized actions. Confidentiality breaches could expose sensitive corporate information or user credentials. Although the vulnerability does not directly affect system integrity or availability, the indirect consequences of compromised user sessions could lead to further attacks or data manipulation. European organizations with strict data protection regulations (e.g., GDPR) may face compliance risks if user data is exposed due to this vulnerability.

1. Immediate upgrade to MoonShine version 3.12.5 or later, where the vulnerability is fixed, is the most effective mitigation. 2. If upgrading is not immediately feasible, implement strict input validation and sanitization on the CutCode Link parameter to disallow any non-HTTPS protocols, explicitly blocking "javascript:" and other potentially dangerous schemes. 3. Employ Content Security Policy (CSP) headers to restrict the execution of inline scripts and limit the sources of executable scripts to trusted domains only. 4. Conduct a thorough audit of existing articles to identify and remove any malicious or suspicious CutCode Link entries. 5. Restrict article creation and update permissions to trusted users only, minimizing the risk of privilege abuse. 6. Educate content managers about the risks of injecting untrusted links or code. 7. Monitor application logs and user activity for unusual behavior indicative of exploitation attempts. 8. Implement web application firewall (WAF) rules to detect and block attempts to inject "javascript:" payloads in article parameters.