CVE-2026-85191 in Tabs & Accordions Extension
Summary
by MITRE • 09/14/2026
Joomla Extension - regularlabs.com - Privileged stored XSS via rtla-alias option in Tabs & Accordions extension for Joomla < 3.1.0 - Tabs & Accordions rewrites links matching an item alias into calls to its browser API. The affected renderer places the alias inside a quoted JavaScript argument in an HTML onclick attribute without securing both the JavaScript-string and HTML-attribute contexts. A crafted data-rlta-alias value can therefore change the generated handler.
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Analysis
by VulDB Data Team • 09/14/2026
The vulnerability identified involves a privileged stored cross-site scripting (XSS) flaw within the Tabs & Accordions extension for Joomla, specifically affecting versions prior to 3.1.0 developed by regularlabs.com. This security issue stems from improper input validation and context-insensitive output encoding when handling user-supplied data. The core of the vulnerability lies in how the extension processes item aliases through its rtla-alias option. When a content administrator or any privileged user creates or edits an article, they can specify an alias for that item. This alias is then utilized by the Tabs & Accordions renderer to generate dynamic links intended to trigger browser API calls via JavaScript event handlers embedded directly within HTML attributes.
The technical flaw arises from the failure to properly escape data when placing it into a quoted JavaScript argument inside an HTML onclick attribute. The application takes the raw value of the alias and inserts it without securing either the JavaScript-string context or the surrounding HTML-attribute context. This lack of dual-context encoding allows an attacker who has write access to content, such as a registered user with publishing privileges or an administrator, to inject malicious script code. By crafting a specific data-rlta-alias value that includes closing quotes and additional JavaScript commands, the attacker can break out of the intended string boundary. This manipulation alters the structure of the generated HTML handler, effectively allowing arbitrary JavaScript execution in the context of any user who views the affected content.
From an operational impact perspective, this stored XSS vulnerability poses a significant risk to both site administrators and end-users. Because the malicious payload is stored within the database as part of the article alias, it persists until manually removed or corrected by an administrator. When other users visit pages containing tabs or accordions that reference these compromised items, their browsers execute the injected scripts automatically. This can lead to session hijacking through cookie theft, redirection to phishing sites, defacement of the website interface, or further propagation of malware if combined with browser-specific exploits. The privileged nature of the initial injection vector means that lower-level users cannot trigger this vulnerability directly but rely on higher-privileged accounts to inadvertently store the payload, making detection and remediation more complex as it requires auditing content created by trusted roles.
This vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. Specifically, it represents a stored variant where malicious scripts are permanently stored on the target server. In terms of offensive security frameworks, this maps to MITRE ATT&CK technique T1059, Command and Scripting Interpreter, specifically under sub-techniques involving JavaScript execution within web browsers. The attack vector leverages the browser's native capabilities to execute code without requiring additional plugins or external file uploads, relying solely on standard HTML and JavaScript interpretation mechanisms that are inherently trusted by modern browsers.
Mitigation strategies must focus on both immediate remediation and long-term defensive coding practices. Administrators should immediately update the Tabs & Accordions extension to version 3.1.0 or later where this issue has been addressed through proper input sanitization and output encoding. For systems unable to upgrade instantly, manual review of existing content is necessary to identify and remove any aliases containing suspicious characters such as quotes, angle brackets, or script tags. Developers should implement strict context-aware escaping functions that handle both HTML attribute values and JavaScript string literals correctly. Utilizing established security libraries for encoding ensures that special characters are converted into their safe entity equivalents before rendering. Additionally, implementing a Content Security Policy (CSP) can provide an additional layer of defense by restricting the sources from which scripts can be loaded or executed, thereby mitigating the impact even if an injection attempt succeeds. Regular code audits focusing on data flow between user input and HTML output are essential to prevent similar vulnerabilities in future development cycles.