CVE-2026-73393 in Subscribe2 Plugin
Summary
by MITRE • 08/18/2026
Unauthenticated Cross Site Scripting (XSS) in Subscribe2 <= 10.46 versions.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified as an unauthenticated Cross-Site Scripting flaw within the Subscribe2 plugin for WordPress, specifically affecting versions up to and including 10.46, represents a significant security risk due to its lack of authentication requirements. This characteristic allows any remote attacker who can access the public-facing interface of a website running this software to exploit the vulnerability without needing valid credentials or prior authorization. The core technical flaw stems from insufficient input validation and sanitization mechanisms when processing user-supplied data that is subsequently reflected in HTTP responses. In typical web application architectures, inputs such as form fields, URL parameters, or cookie values are often echoed back to the client side for display purposes. When these inputs contain malicious script payloads rather than expected text content, the browser interprets them as executable code, leading to unintended execution within the context of the victim's session.
From a technical perspective, this vulnerability aligns with CWE-79, which is classified under Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The specific subtype here likely involves reflected XSS where the malicious payload is immediately returned to the user without being stored in a database or persistent storage medium. However, even if the reflection occurs via server-side rendering errors or misconfigured template engines within the plugin's codebase, the impact remains severe because it bypasses standard security controls that rely on session validation for sensitive operations. The Subscribe2 plugin is widely used for managing newsletter subscriptions and email notifications in WordPress environments. Its widespread adoption increases the attack surface significantly, making this vulnerability a high-value target for automated scanning tools and opportunistic attackers seeking to compromise large numbers of sites simultaneously through mass exploitation campaigns.
The operational impact of exploiting this unauthenticated XSS can vary depending on the specific payload delivered by the attacker but generally includes session hijacking, credential theft, defacement of the website interface, or redirection of users to malicious phishing sites. By injecting JavaScript code that executes in the victim's browser, an attacker can access cookies containing authentication tokens for administrative accounts if those sessions are active and not properly secured with HttpOnly flags. This capability allows the attacker to impersonate legitimate administrators, potentially gaining full control over the WordPress installation. Furthermore, the vulnerability enables drive-by download attacks where malware is silently installed on visitor devices or facilitates keylogging activities that capture sensitive information typed into forms on the compromised site. The absence of authentication requirements means that even users with no prior relationship to the target website can trigger these malicious actions simply by visiting a crafted URL or interacting with specific plugin features exposed publicly.
Mitigation strategies for this vulnerability must prioritize immediate remediation through software updates and defensive configuration changes. Administrators running Subscribe2 versions 10.46 or earlier should upgrade to the latest patched version released by the developer, which presumably includes proper input sanitization functions such as esc_html() or wp_kses_post() in PHP code before outputting data to HTML contexts. In cases where immediate patching is not feasible due to compatibility concerns with other plugins or custom themes, temporary workarounds may include implementing Web Application Firewall rules that detect and block common XSS payload patterns like script tags, event handlers, and javascript URIs within HTTP request parameters. Additionally enabling Content Security Policy headers can restrict the sources from which scripts are allowed to execute, thereby mitigating the impact of successful injection attempts even if they occur. Regular security audits and code reviews focusing on data flow analysis will help identify similar vulnerabilities in other plugins or custom modules that handle user input without adequate validation mechanisms.