CVE-2025-10135 is a stored cross-site scripting (XSS) vulnerability identified in the WP ViewSTL plugin for WordPress, affecting all versions up to and including 1.0. The vulnerability arises from improper neutralization of input during web page generation, specifically due to insufficient sanitization and output escaping of user-supplied attributes in the plugin's 'viewstl' shortcode. Authenticated attackers with contributor-level access or higher can exploit this flaw by injecting arbitrary JavaScript code into pages via the shortcode parameters. Because the malicious script is stored persistently, it executes every time a user accesses the infected page, potentially allowing attackers to hijack user sessions, steal cookies, perform actions on behalf of other users, or deface the website. The CVSS 3.1 base score is 6.4, reflecting a medium severity with network attack vector (AV:N), low attack complexity (AC:L), privileges required (PR:L), no user interaction (UI:N), and scope changed (S:C). The vulnerability impacts confidentiality and integrity but not availability. No patches or fixes are currently published, and no known exploits have been observed in the wild. The vulnerability was reserved and published in late 2025, with Wordfence as the assigner. This issue highlights the risks of insufficient input validation in WordPress plugins, especially those that allow user-generated content to be embedded in pages without proper sanitization.

For European organizations, this vulnerability poses a moderate risk primarily to the confidentiality and integrity of web applications running WordPress with the WP ViewSTL plugin installed. Exploitation could lead to session hijacking, unauthorized actions performed under legitimate user contexts, and potential defacement or misinformation on corporate websites. Organizations that allow contributor-level access to external or internal users increase their exposure. While availability is not directly impacted, the reputational damage and potential data leakage could have significant business consequences. Given the widespread use of WordPress across Europe, especially in small and medium enterprises, educational institutions, and government websites, the vulnerability could be leveraged for targeted attacks or lateral movement within networks. The absence of known exploits in the wild currently reduces immediate risk, but the ease of exploitation and low complexity suggest attackers may develop exploits soon after disclosure. Compliance with GDPR may also be impacted if personal data is compromised through such attacks.

1. Immediately audit WordPress installations to identify the presence of the WP ViewSTL plugin and determine the version in use. 2. Until an official patch is released, consider disabling or removing the WP ViewSTL plugin to eliminate the attack surface. 3. Restrict contributor-level permissions to trusted users only and review user roles to minimize the number of users who can inject content via shortcodes. 4. Implement web application firewalls (WAFs) with rules to detect and block suspicious shortcode attribute inputs or known XSS payload patterns targeting this plugin. 5. Employ Content Security Policy (CSP) headers to limit the impact of injected scripts by restricting script execution sources. 6. Monitor website logs and user activity for unusual behavior indicative of exploitation attempts. 7. Educate content contributors about safe content practices and the risks of injecting untrusted code. 8. Once a patch is available, promptly apply updates and verify that input sanitization and output escaping are properly enforced. 9. Conduct regular security assessments focusing on plugin vulnerabilities and user privilege management.