WordPress UpSolution Core plugin <= 8.41 - Reflected Cross Site Scripting (XSS) vulnerability

An attacker exploiting this Reflected XSS vulnerability can inject arbitrary JavaScript code into web pages served by the UpSolution Core plugin. This code can then execute in the context of a victim's browser, allowing the attacker to steal cookies, session tokens, or other sensitive information. They could also redirect users to malicious websites, deface the website, or perform actions on behalf of the victim without their knowledge. The impact is particularly severe if the website handles sensitive user data or financial transactions, as an attacker could gain access to this information. While this is a reflected XSS, the potential for widespread impact on a WordPress site is significant.

Websites using the UpSolution Core plugin, particularly those with user input forms or features that allow users to contribute content, are at risk. Shared hosting environments where multiple websites share the same server resources are also at increased risk, as a compromise of one website could potentially lead to the compromise of others.

• wordpress / composer / npm:

grep -r '<script>' /var/www/html/wp-content/plugins/us-core/*

• generic web:

curl -I https://example.com/vulnerable-page?input=<script>alert('XSS')</script>

• wordpress / composer / npm:

wp plugin list --status=inactive | grep us-core

• wordpress / composer / npm:

wp plugin update us-core

1. 2026-03-25Disclosure

   disclosure

1. 予約済み2026-01-28
2. 公開日2026-03-25
3. 更新日2026-04-28
4. EPSS 更新日2026-04-02

The primary mitigation for CVE-2026-24983 is to immediately upgrade the UpSolution Core plugin to version 8.42 or later. If upgrading is not immediately feasible due to compatibility issues or testing requirements, consider implementing a Web Application Firewall (WAF) rule to filter out potentially malicious input that could trigger the XSS vulnerability. Specifically, look for patterns indicative of JavaScript injection attempts in user-supplied input fields. Additionally, carefully review and sanitize all user input before rendering it in web pages to prevent future XSS vulnerabilities. After upgrading, confirm the fix by attempting to inject a simple JavaScript payload (e.g., <script>alert('XSS')</script>) through a vulnerable input field; it should not execute.