CVE-2026-102425 in Forms Extension
Summary
by MITRE • 09/29/2026
Joomla Extension - balbooa.com - Unauthenticated RCE via field shortcode injection in Balbooa Forms < 2.4.3.4 - Balbooa Forms supports administrator-defined PHP code which runs after a public form submission. The feature also supports form-field shortcodes inside that PHP. Before calling `eval()`, the component replaces each shortcode with the raw value submitted by the visitor, leading to an RCE vector. A public form must use the product's optional PHP-after-submission action and interpolate an attacker-controlled field shortcode inside a double-quoted PHP string to be vulnerable.
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Analysis
by VulDB Data Team • 09/29/2026
The vulnerability identified in Balbooa Forms versions prior to 2.4.3.4 represents a critical server-side code injection flaw that allows unauthenticated attackers to achieve remote code execution on Joomla-based websites. This component is designed to facilitate the creation of public forms, offering administrators advanced capabilities such as defining custom PHP scripts that execute after a form submission event. While this feature provides significant flexibility for developers and site owners, it introduces a severe security risk when combined with shortcodes used within those scripts. The core issue lies in how the application processes these shortcodes before evaluating the embedded PHP code. Specifically, the system replaces placeholders representing form fields with their raw submitted values without adequate sanitization or context-aware escaping prior to passing the string to the eval function for execution.
From a technical perspective, this flaw is classified as CWE-94 Improper Control of Generation of Code (Code Injection). The vulnerability manifests when an administrator configures a public-facing form to include PHP code in the post-submission action and utilizes field shortcodes within double-quoted strings inside that PHP block. When a user submits such a form, the application retrieves the input values associated with those fields and substitutes them directly into the PHP string. Because this substitution occurs before the eval function is invoked, any malicious payload embedded by an attacker in the form fields becomes part of the executable code structure. For instance, if an attacker inputs a value containing closing quotes followed by arbitrary PHP commands, these commands are seamlessly integrated into the script and executed with the privileges of the web server process. This mechanism effectively bypasses standard input validation measures because the injection point is not within the data storage layer but rather in the dynamic code generation phase.
The operational impact of this vulnerability is severe, as it grants unauthenticated remote attackers full control over the underlying system hosting the Joomla installation. Since PHP scripts executed by eval typically run with the same permissions as the web server user, successful exploitation can lead to complete compromise of the website's files and database. Attackers can use this access to deface websites, steal sensitive data such as user credentials or personal information stored in the CMS, install backdoors for persistent access, or pivot further into internal network infrastructure if the server is accessible from within a trusted zone. The requirement that the form must be public and configured with specific PHP-after-submission actions limits the attack surface slightly but does not mitigate the severity of the exploit once those conditions are met. This aligns with ATT&CK technique T1059 Command and Scripting Interpreter, specifically focusing on code injection vectors where attackers leverage legitimate system features to execute unauthorized commands.
To remediate this vulnerability, organizations must immediately update Balbooa Forms to version 2.4.3.4 or later, which addresses the improper handling of shortcodes during evaluation. In addition to applying vendor patches, administrators should review existing forms for any configuration that utilizes PHP code in post-submission actions containing field shortcodes within double-quoted strings. If such configurations are necessary and cannot be avoided due to legacy requirements, strict input validation must be implemented at the application level before data is passed into dynamic evaluation contexts. This includes ensuring that all user-supplied inputs are properly escaped or encoded based on their context within PHP code structures. Furthermore, implementing a Web Application Firewall with rules capable of detecting common command injection patterns can provide an additional layer of defense against exploitation attempts while patching efforts are underway. Regular security audits and adherence to secure coding practices regarding dynamic code execution are essential to prevent similar vulnerabilities in future development cycles.