CVE-2026-57743 in RT-Theme 18 Plugin
Summary
by MITRE • 07/13/2026
Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion') vulnerability in stmcan RT-Theme 18 | Extensions rt18-extensions allows PHP Local File Inclusion.This issue affects RT-Theme 18 | Extensions: from n/a through <= 2.5.
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Analysis
by VulDB Data Team • 07/13/2026
The vulnerability under discussion represents a critical improper control of filename for include/require statements in PHP applications, specifically manifesting as a PHP Remote File Inclusion (RFI) weakness within the stmcan RT-Theme 18 | Extensions rt18-extensions plugin. This flaw resides in the core functionality that processes file inclusion operations, where user-supplied input directly influences the filename parameter used in PHP's include or require functions without adequate sanitization or validation measures.
The technical implementation of this vulnerability stems from the plugin's failure to properly validate and sanitize user-provided parameters before using them in file inclusion contexts. When an attacker can manipulate the filename parameter passed to include/require statements, they gain the ability to execute arbitrary PHP code on the target server. This occurs because the application does not implement proper input validation or whitelisting mechanisms, allowing malicious actors to inject URLs or local file paths that point to attacker-controlled resources.
The operational impact of this vulnerability extends beyond simple code execution capabilities, as it provides attackers with potential access to sensitive system information and unauthorized administrative privileges. The vulnerability affects versions from n/a through 2.5 of the rt18-extensions plugin, indicating a widespread exposure across multiple releases. Attackers can leverage this weakness to establish persistent backdoors, exfiltrate database credentials, or escalate privileges within the compromised WordPress environment.
Security standards such as CWE-98 and CWE-434 categorize this vulnerability type under improper control of filename for include operations and improper restriction of a pathname to a restricted directory. The ATT&CK framework would classify this as part of the T1059.007 technique involving scripting languages, specifically targeting the execution of malicious code through PHP include functions. Additionally, this vulnerability aligns with the T1190 technique related to exploitation of remote file inclusion vulnerabilities, demonstrating how attackers can leverage poorly validated input to gain unauthorized access to server resources.
Mitigation strategies should prioritize immediate patch deployment for the affected versions and implementation of proper input validation mechanisms that sanitize all user-supplied parameters before they reach include/require statements. Organizations must enforce strict parameter validation through whitelisting approaches, implement proper file path restrictions, and consider using PHP's open_basedir configuration directive to limit file access to specific directories. Network-level protections such as web application firewalls can provide additional defense-in-depth layers, while regular security audits and code reviews should be implemented to prevent similar vulnerabilities in future development cycles.
The remediation process requires immediate attention from system administrators to upgrade to patched versions of the rt18-extensions plugin, as well as comprehensive review of all PHP applications for similar inclusion vulnerabilities. Security teams should conduct thorough penetration testing to identify potential exploitation vectors and implement proper logging mechanisms to detect suspicious file inclusion attempts. Regular security training for developers regarding secure coding practices, particularly around input validation and file handling operations, remains crucial in preventing such vulnerabilities from being introduced into production systems.