Error htmlspecialchars(): Argument #1 ($string) must be of type string, array given when processing parameters retrieved from the database in Joomla

[vetka-nn]

Issue Description:

When working with Joomla, the following error occurred: htmlspecialchars(): Argument #1 ($string) must be of type string, array given. After thorough analysis, it became clear that this error is not related to any third-party plugin or custom code. The issue arises from Joomla’s core when it tries to process parameters retrieved from the database, passing an array instead of a string to the htmlspecialchars function.

Steps to Reproduce:

1. Configure a plugin or component with a parameter that may return an array (e.g., configuration parameters with multiple selections).
2. Use a standard Joomla method to retrieve this parameter from the database.
3. Joomla attempts to process the value as a string, but if the parameter is returned as an array, it causes an error when passed to htmlspecialchars.

Root Cause:

The issue occurs due to a lack of type checking for values retrieved from the database before processing. In the current version of Joomla, a parameter may be returned as an array, but the system does not verify this before passing it to functions expecting a string. Consequently, when Joomla tries to use htmlspecialchars on an array, a type error occurs.

Solution Implemented:

To resolve this issue, I manually added type-checking on the variable. If the parameter is an array, it is converted to a string using implode. This resolved the error.

Suggested Improvement:

In Joomla’s core code, a type check should be added before passing values to htmlspecialchars or other functions that expect a string. If the value is an array, it should be converted to a string. This improvement would make Joomla more robust and prevent similar errors when handling parameters that may contain arrays.

Example of the fix:

File: SITE_ROOT/layouts/joomla/form/field/text.php

String: 117

Was:

value="<?php echo htmlspecialchars($value, ENT_COMPAT, 'UTF-8'); ?>"

Now:

value="<?php
$value = is_array($value) ? implode(', ', $value) : $value; 
echo htmlspecialchars($value, ENT_COMPAT, 'UTF-8'); 
?>"

Conclusion:

This issue is caused by Joomla’s handling of parameters rather than by any third-party plugin. The proposed fix would improve Joomla’s stability and compatibility with various configuration parameters and their values.### Steps to reproduce the issue

System information:

Setting 	Value
PHP Built On 	Linux vh438 5.15.0-121-generic #131-Ubuntu SMP Fri Aug 9 08:29:53 UTC 2024 x86_64
Database Type 	mysql
Database Version 	8.0.37-29
Database Collation 	utf8mb4_0900_ai_ci
Database Connection Collation 	utf8mb4_0900_ai_ci
Database Connection Encryption 	None
Database Server Supports Connection Encryption 	No
PHP Version 	8.2.17
Web Server 	Apache/2.4.52
WebServer to PHP Interface 	apache2handler
Joomla! Version 	Joomla! 5.2.1 Stable [ Uthabiti ] 7-November-2024 17:00 GMT
Joomla Backward Compatibility Plugin 	Enabled ()
User Agent 	Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:132.0) Gecko/20100101 Firefox/132.0 

[Hackwar]

The problem is, that your database contains more than one value for a field which should only contain one value. But indeed, the error handling could be better.