CVE-2018-16283 in Wechat Broadcast Plugin
Summary
by MITRE
The Wechat Broadcast plugin 1.2.0 and earlier for WordPress allows Directory Traversal via the Image.php url parameter.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/26/2025
The vulnerability identified as CVE-2018-16283 affects the Wechat Broadcast plugin version 1.2.0 and earlier within the WordPress ecosystem, representing a critical directory traversal flaw that exposes systems to unauthorized file access. This vulnerability resides in the image.php component of the plugin and specifically targets the url parameter which fails to properly validate or sanitize user input. The flaw enables attackers to manipulate the url parameter to traverse directories within the web server filesystem, potentially gaining access to sensitive files, configuration data, or even executing arbitrary code depending on the server configuration and file permissions. Directory traversal vulnerabilities of this nature are particularly dangerous because they can be exploited to bypass normal access controls and retrieve confidential information that should remain protected.
The technical implementation of this vulnerability stems from improper input validation within the plugin's image handling functionality. When the url parameter is processed without adequate sanitization, attackers can inject malicious path traversal sequences such as ../ or ../../ to navigate beyond the intended directory boundaries. This weakness directly maps to CWE-22, which categorizes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability exists because the plugin does not implement proper input validation or canonicalization of the url parameter before using it to construct file paths. This allows attackers to craft malicious URLs that can access files outside the plugin's intended scope, potentially leading to complete system compromise.
The operational impact of CVE-2018-16283 extends beyond simple information disclosure, as it can lead to full system compromise and persistent backdoor access. An attacker who successfully exploits this vulnerability can potentially access database configuration files, wp-config.php, plugin files, theme files, and user credentials stored in the WordPress installation. The attack surface is particularly concerning for WordPress installations where the plugin is active, as it provides a direct pathway to compromise the entire web application and potentially the underlying server infrastructure. This vulnerability can be exploited by attackers with minimal technical expertise, making it a high-risk issue that requires immediate remediation. The impact is further amplified when considering that many WordPress installations are deployed in environments where the web server has elevated privileges, increasing the potential for privilege escalation and system-wide compromise.
Mitigation strategies for this vulnerability must include immediate patching of the Wechat Broadcast plugin to version 1.2.1 or later, which contains the necessary input validation fixes. System administrators should also implement proper network segmentation and access controls to limit exposure of vulnerable WordPress installations. The implementation of web application firewalls with rules specifically targeting directory traversal patterns can provide additional defense-in-depth measures. Input validation should be strengthened at multiple layers including the application code level where the url parameter is processed, and at the server level through proper file permissions and access controls. Security monitoring should be enhanced to detect suspicious file access patterns and unusual directory traversal attempts. Organizations should also consider implementing principle of least privilege for web server accounts and regularly audit plugin installations to ensure no vulnerable components remain active. This vulnerability highlights the importance of proper input validation and the necessity of following secure coding practices as outlined in the OWASP Top Ten and MITRE ATT&CK framework, particularly in the context of web application security controls and defensive measures against path traversal attacks.