CVE-2026-77028 in Zoo Extension
Summary
by MITRE • 08/21/2026
Joomla Extension - yootheme.com - Reflected XSS and open redirect via the submission redirect parameter in Zoo < 4.1.66
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Analysis
by VulDB Data Team • 08/21/2026
The vulnerability identified in YOOtheme's Zoo extension for Joomla, specifically affecting versions prior to 4.1.66, represents a significant security risk stemming from inadequate input validation within the application's redirection logic. This flaw allows attackers to exploit two distinct but related attack vectors: reflected cross-site scripting and open redirects. The core issue resides in how the software handles user-supplied data passed through specific submission parameters intended for redirecting users after form interactions or actions are completed. When a request is made containing maliciously crafted input, the application fails to properly sanitize or validate this data before processing it, leading directly to the execution of arbitrary code or unauthorized navigation redirections depending on the payload utilized by the attacker.
From a technical perspective, the reflected cross-site scripting vulnerability arises because the unvalidated redirect parameter is often echoed back into the HTTP response without adequate encoding. This allows an attacker to inject JavaScript payloads that are executed in the context of the victim's browser session when they interact with a specially crafted link or form submission. The impact of this XSS vector includes the potential theft of sensitive user data such as session cookies, authentication tokens, and personal information entered into forms on the site. Furthermore, it enables attackers to perform actions on behalf of the authenticated user, potentially leading to account takeover if administrative privileges are involved. This aligns with CWE-79, which classifies improper neutralization of input during web page generation, a common root cause for cross-site scripting flaws in web applications that fail to implement consistent output encoding strategies across all dynamic content injection points.
Concurrently, the open redirect vulnerability presents a different but equally dangerous threat vector by allowing attackers to manipulate the destination URL used after an action is completed. By supplying a malicious external domain as part of the redirect parameter, an attacker can trick users into visiting phishing sites or malware distribution centers while maintaining the illusion that they are still on the legitimate Joomla site due to the initial trusted domain in the URL path. This technique is frequently employed in social engineering attacks where trust associated with the original website lowers the victim's suspicion regarding the legitimacy of the subsequent destination page. This flaw corresponds directly to CWE-601, which describes open redirect vulnerabilities resulting from insufficient validation of user-controlled input used for redirection purposes. The presence of this vulnerability undermines the integrity of the application’s navigation flow and can be leveraged in broader attack chains involving credential harvesting or malware delivery.
The operational impact of these combined vulnerabilities is severe, particularly given that Zoo is a widely used page builder and content management extension within the Joomla ecosystem. A successful exploitation could compromise not only individual user accounts but also potentially lead to full site takeover if an administrator falls victim to such attacks. The ability to execute arbitrary scripts or redirect users without warning erodes trust in the platform and exposes organizations using this software to significant data breach risks, regulatory compliance failures under standards like GDPR, and reputational damage. Attackers can automate these exploits through phishing campaigns or by embedding malicious links in social media posts, making them accessible even to low-skilled threat actors who utilize existing exploit frameworks that target common web application flaws.
To mitigate these vulnerabilities, immediate action is required to update the YOOtheme Zoo extension to version 4.1.66 or later, where the developers have implemented proper input validation and output encoding mechanisms. Administrators should ensure that all third-party extensions are kept up-to-date with their latest security patches, as outdated software remains a primary entry point for automated scanning tools used by malicious actors. Additionally, implementing Content Security Policy headers can provide an additional layer of defense against cross-site scripting attacks by restricting the sources from which scripts can be loaded and executed within the browser environment. For open redirects, developers should enforce allow-listing techniques where only predefined trusted domains are permitted as redirect targets, rather than relying solely on blacklist approaches or simple string checks that can often be bypassed through encoding tricks or protocol variations such as using // instead of http:// to trigger relative URL resolution behaviors in browsers.
Security monitoring and logging practices should also be enhanced to detect attempts at exploiting these flaws. By analyzing web server logs for unusual patterns in redirect parameters, particularly those containing suspicious domains or encoded script tags, security teams can identify ongoing exploitation attempts and respond accordingly. Integrating this vulnerability into threat intelligence feeds allows organizations using ATT&CK framework mappings to better understand the tactical context of such attacks, recognizing them as part of initial access strategies involving phishing or drive-by downloads via compromised legitimate sites. Regular penetration testing focused on input validation and redirection logic will help identify similar weaknesses in other custom modules or extensions that may share the same architectural flaws within the Joomla environment.