CVE-2025-50183 is a stored Cross-site Scripting (XSS) vulnerability affecting OpenList, a product developed by OpenListTeam. The vulnerability exists in the frontend UI component of OpenList, specifically in the file preview and browsing feature prior to version 4.0.0-rc.4. The issue arises when files with a .py extension containing JavaScript code wrapped in <script> tags are processed. In certain modes, these files are interpreted and executed as HTML, allowing malicious JavaScript to run in the context of the user's browser. This improper neutralization of input during web page generation corresponds to CWE-79. The vulnerability does not require authentication (PR:N) but does require user interaction (UI:R), such as viewing or browsing the malicious file. The CVSS v3.1 score is 6.5 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), no privileges required, user interaction required, unchanged scope, high confidentiality impact, but no impact on integrity or availability. Although no known exploits are reported in the wild yet, the vulnerability allows an attacker to execute arbitrary JavaScript in the victim's browser, potentially leading to theft of sensitive information such as session cookies or other confidential data accessible in the browser context. The issue has been patched in version 4.0.0-rc.4 of OpenList, and users are strongly advised to upgrade to this or later versions to mitigate the risk.

For European organizations using OpenList versions prior to 4.0.0-rc.4, this vulnerability poses a significant risk to confidentiality. An attacker can inject malicious scripts that execute in the browsers of users who preview or browse .py files, potentially leading to session hijacking, data theft, or unauthorized actions performed on behalf of the user. While the vulnerability does not affect integrity or availability directly, the confidentiality breach can have severe consequences, especially for organizations handling sensitive or regulated data such as personal information, intellectual property, or financial records. The risk is heightened in sectors like finance, healthcare, government, and critical infrastructure, where data confidentiality is paramount. Additionally, since no authentication is required to exploit the vulnerability, attackers can target any user with access to the vulnerable OpenList instance, increasing the attack surface. The requirement for user interaction means that social engineering or phishing tactics could be used to lure users into triggering the exploit. The lack of known exploits in the wild suggests the threat is currently theoretical but could become active if attackers develop proof-of-concept code. European organizations should consider the potential for targeted attacks exploiting this vulnerability, especially given the increasing regulatory scrutiny around data protection (e.g., GDPR).

1. Immediate upgrade: Organizations should upgrade OpenList to version 4.0.0-rc.4 or later, where the vulnerability is patched. 2. Input validation and sanitization: Until the upgrade is applied, implement strict input validation and sanitization on the server side to prevent execution of embedded scripts in .py files or any file previews. 3. Content Security Policy (CSP): Deploy a robust CSP header to restrict the execution of inline scripts and limit the sources from which scripts can be loaded, reducing the impact of any injected scripts. 4. User awareness: Educate users about the risks of opening or previewing untrusted files within OpenList, emphasizing caution with .py files or files from unknown sources. 5. Access controls: Restrict file upload and browsing permissions to trusted users only, minimizing the chance of malicious files being introduced. 6. Monitoring and logging: Enable detailed logging of file preview activities and monitor for unusual patterns or attempts to access suspicious files. 7. Web Application Firewall (WAF): Configure WAF rules to detect and block common XSS payloads targeting the file preview feature. 8. Incident response readiness: Prepare to respond to potential exploitation attempts by having processes in place to quickly investigate and remediate incidents involving OpenList.