CVE-2025-3890 is a stored cross-site scripting vulnerability identified in the WordPress Simple Shopping Cart plugin developed by mra13. The flaw exists in all versions up to and including 5.1.3, specifically within the 'wp_cart_button' shortcode, which fails to properly sanitize and escape user-supplied attributes before rendering them on web pages. This improper neutralization of input (CWE-79) allows authenticated attackers with contributor-level privileges or higher to inject arbitrary JavaScript code into pages. When other users access these pages, the injected scripts execute in their browsers, potentially compromising session tokens, redirecting users, or performing actions on their behalf. The vulnerability is remotely exploitable over the network without user interaction beyond page viewing, but requires the attacker to have authenticated access with contributor or higher permissions. The CVSS v3.1 base score is 6.4, reflecting a medium severity with low attack complexity and no requirement for user interaction, but limited by the need for authentication. No patches or official fixes were linked at the time of disclosure, and no known exploits were reported in the wild. The vulnerability affects a widely used e-commerce plugin for WordPress, a platform powering a significant portion of websites globally, making the issue relevant to many organizations running WordPress-based online stores or sites using this plugin.

The impact of CVE-2025-3890 is primarily on the confidentiality and integrity of affected WordPress sites. Successful exploitation enables attackers to execute arbitrary scripts in the context of the victim's browser, which can lead to theft of session cookies, user impersonation, unauthorized actions on behalf of users, and potential defacement or redirection to malicious sites. Since the vulnerability is stored XSS, the malicious payload persists and affects all users who visit the compromised page, increasing the scope of impact. Although availability is not directly affected, the reputational damage and potential data breaches can be significant. Organizations with contributor-level users are at risk of internal threat actors or compromised accounts exploiting this flaw. Given WordPress's extensive use worldwide, especially for e-commerce, this vulnerability could facilitate targeted attacks against online stores, customer data theft, and broader compromise of web infrastructure.

To mitigate CVE-2025-3890, organizations should first check for updates or patches from the plugin vendor and apply them promptly once available. In the absence of official patches, administrators should restrict contributor-level access to trusted users only and audit existing users for suspicious accounts. Implementing a Web Application Firewall (WAF) with rules to detect and block malicious script injections targeting the 'wp_cart_button' shortcode parameters can reduce risk. Additionally, site owners can temporarily disable or remove the vulnerable shortcode usage in content until a fix is applied. Employing Content Security Policy (CSP) headers to restrict script execution sources can help mitigate the impact of injected scripts. Regular security scanning and monitoring for unusual activity or injected content on pages using the plugin are recommended. Finally, educating contributors about safe input practices and monitoring for suspicious behavior can prevent exploitation.