CVE-2026-102398 in Popup Plugin
Summary
by MITRE • 09/30/2026
Unauthenticated Cross Site Scripting (XSS) in Popup by Supsystic <= 1.13.1 versions.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability identified as an unauthenticated cross-site scripting flaw within the Popup plugin for WordPress, specifically affecting versions up to and including 1.13.1, represents a significant security risk due to its lack of authentication requirements. This classification indicates that any user visiting a website utilizing this vulnerable version can exploit the defect without needing valid credentials or prior login access. The core technical flaw lies in the insufficient sanitization and validation of input data processed by the plugin's popup functionality. When users interact with elements controlled by the plugin, such as form fields within popups or parameters passed via URL queries that trigger specific display behaviors, malicious scripts can be injected into the application context. Because these inputs are not properly escaped before being rendered in the browser, they execute arbitrary JavaScript code under the security privileges of the victim's session and the domain hosting the vulnerable site.
From a technical perspective, this vulnerability typically stems from improper output encoding or missing input validation mechanisms within the PHP backend logic that generates the popup content. The attacker crafts a specific payload containing malicious JavaScript, often utilizing event handlers like onload or onerror to trigger execution upon page load or image failure respectively. This code is then embedded into parameters such as title fields, description text areas, or custom attributes managed by the plugin. When the server processes this request and returns the HTML response, the browser interprets the injected script as legitimate content belonging to the site's domain. This allows the attacker to bypass same-origin policy restrictions, enabling them to access sensitive data stored in cookies, local storage, or session tokens associated with authenticated users who visit the compromised page.
The operational impact of this vulnerability is severe and multifaceted. Primarily, it facilitates account takeover attacks if an administrator or privileged user visits a maliciously crafted link containing the exploit payload. The injected script can exfiltrate administrative cookies to the attacker's server, allowing full control over the WordPress installation. Beyond privilege escalation, attackers can use this vector for phishing campaigns by dynamically modifying the page content to display fake login forms that steal credentials from unsuspecting visitors. Additionally, the vulnerability enables defacement of the website appearance and distribution of malware through drive-by downloads or redirections to malicious sites. Since the attack is unauthenticated, it significantly lowers the barrier to entry for attackers, making automated scanning tools highly effective at identifying and exploiting this weakness across thousands of vulnerable installations simultaneously.
This flaw aligns with CWE-79, which defines Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. It also maps closely to MITRE ATT&CK technique T1059.007, specifically JavaScript execution within a browser environment, and potentially T1189 Drive-by Compromise if the payload leads to malware installation. The unauthenticated nature of the exploit places it in high severity categories according to common vulnerability scoring systems due to its ease of exploitation and broad potential impact on data confidentiality and integrity.
Mitigation strategies must prioritize immediate remediation through software updates. Administrators running versions 1.13.1 or earlier should upgrade to the latest patched version released by Supsystic, which implements proper input sanitization using functions like wp_kses_post or esc_html depending on the context of data rendering. In cases where updating is not immediately feasible, temporary workarounds include implementing a Web Application Firewall rule that detects and blocks common XSS payload patterns in POST and GET requests targeting popup-related endpoints. Additionally, enforcing strict Content Security Policy headers can mitigate the impact by restricting script execution sources, although this requires careful configuration to avoid breaking legitimate site functionality. Regular security audits and code reviews focusing on input validation practices are essential for preventing similar vulnerabilities in future development cycles.