CVE-2026-101126 in Forms Extension
Summary
by MITRE • 09/29/2026
Joomla Extension - balbooa.com - File meta data tampering in Balbooa Forms < 2.4.3.4 - The final form submission processes JSON arrays per upload field, checking only that IDs are numeric. Client-supplied filenames and display names are trusted directly, introducing potential cross-session claiming, metadata tampering, and path traversal risks (e.g., via getFilePath())
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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 failure in input validation and trust management within the Joomla extension's file upload handling mechanism. This flaw stems from an insufficient sanitization process applied to metadata associated with uploaded files, specifically targeting client-supplied filenames and display names. When a user submits a form containing file uploads, the backend processes these inputs by parsing JSON arrays that correspond to each upload field. The security architecture of this component relies heavily on verifying that specific identifiers are numeric, which serves as a basic integrity check for internal references. However, this validation is superficial because it fails to enforce strict constraints on string-based attributes such as filenames and display labels. By trusting these client-supplied values directly without proper encoding or restriction, the application creates an attack surface where malicious actors can inject arbitrary data into the system's file management logic.
The operational impact of this vulnerability is multifaceted, encompassing cross-session claiming, metadata tampering, and path traversal risks. Cross-session claiming occurs when an attacker manipulates filenames to associate uploaded files with different user sessions or administrative contexts than intended, potentially leading to unauthorized access to sensitive documents stored on the server. Metadata tampering allows attackers to alter how files are presented in the interface or database records, which can be exploited for phishing attacks if trusted file names are displayed to other users without verification. Furthermore, path traversal risks emerge because functions like getFilePath() may interpret maliciously crafted filenames containing directory traversal sequences such as dot-dot-slash characters. If these sequences are not neutralized before being concatenated with base directories, an attacker could potentially read or overwrite files outside the intended upload directory, leading to remote code execution if executable scripts can be placed in accessible locations and subsequently invoked by the web server.
From a technical classification perspective, this vulnerability aligns closely with CWE-20 Improper Input Validation and CWE-74 Injection in Incorrect Context. The failure to validate that filenames do not contain path traversal characters or special symbols constitutes an injection flaw where user input is interpreted as part of a command or file path structure rather than pure data. Additionally, the lack of proper output encoding for display names relates to CWE-80 Cross-site Scripting if those values are rendered in HTML contexts without escaping, although the primary risk here remains server-side manipulation and unauthorized access. In terms of offensive security frameworks, this vulnerability facilitates techniques associated with ATT&CK T1564 Hidden Files and Directories through path traversal attempts and potentially T1078 Valid Accounts for session hijacking if cross-session claiming leads to privilege escalation or data exfiltration in a multi-tenant environment.
Mitigation strategies must focus on implementing strict allow-listing for file names and enforcing rigorous sanitization protocols before any metadata is processed or stored. Developers should ensure that filenames are stripped of all non-alphanumeric characters except for standard extensions, effectively neutralizing path traversal sequences like dot-dot-slash. It is also critical to implement server-side validation that verifies the final resolved file path remains within an expected directory structure, preventing escape attempts regardless of how creative the input might be. Additionally, display names should undergo HTML entity encoding when rendered in user interfaces to prevent any potential cross-site scripting vectors, although this does not address the core metadata tampering issue. Upgrading to version 2.4.3.4 or later is essential as it addresses these validation gaps by enforcing stricter constraints on all file-related inputs during the submission process.