CVE-2018-19458 in PHP Proxy
Summary
by MITRE
In PHP Proxy 3.0.3, any user can read files from the server without authentication due to an index.php?q=file:/// LFI URI, a different vulnerability than CVE-2018-19246.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/30/2025
The vulnerability identified as CVE-2018-19458 represents a critical server-side file inclusion flaw in PHP Proxy version 3.0.3 that allows unauthorized users to access sensitive server files without proper authentication. This issue manifests through a specific URI pattern where the parameter q accepts file:// URI schemes, enabling attackers to traverse the file system and retrieve arbitrary files from the server. The vulnerability operates independently from CVE-2018-19246, indicating a distinct attack vector that specifically targets the proxy's URI handling mechanism rather than other potential weaknesses in the application.
This security flaw fundamentally stems from insufficient input validation and sanitization within the PHP Proxy application's request processing logic. When the application receives a request containing the q parameter with a file:// URI scheme, it fails to properly validate or restrict the file paths that can be accessed, allowing direct file system traversal. The vulnerability is classified as a local file inclusion (LFI) attack vector under CWE-98, which specifically addresses the issue of allowing attackers to include local files through untrusted input. The flaw exists because the application does not properly implement access controls or path validation mechanisms to prevent unauthorized file system access.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with the ability to read any file on the server that the application process has permission to access. This includes configuration files, database credentials, application source code, log files, and potentially sensitive user data stored on the server. Attackers can exploit this vulnerability to gather intelligence about the application's architecture, identify potential attack surfaces, and extract sensitive information that could be used for further exploitation. The lack of authentication requirements means that any user with access to the vulnerable proxy can immediately exploit this flaw, making it particularly dangerous in environments where the proxy is publicly accessible or exposed to untrusted users.
The attack surface for this vulnerability extends beyond simple file reading, as it can be leveraged as a stepping stone for more sophisticated attacks within the network. According to ATT&CK framework, this vulnerability maps to T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachment) where attackers can use the retrieved files to identify system configurations and potentially extract credentials for further lateral movement. Organizations should implement multiple layers of defense including input validation, access control restrictions, and network segmentation to prevent exploitation of this vulnerability. The recommended mitigation strategies include upgrading to a patched version of PHP Proxy, implementing proper input validation for URI parameters, restricting file system access permissions, and monitoring for suspicious file access patterns in application logs.
The vulnerability demonstrates a fundamental weakness in the application's security architecture where proper input sanitization and access control mechanisms are missing. Organizations should conduct comprehensive security assessments of their proxy applications and similar tools to identify similar vulnerabilities that could be exploited through similar attack vectors. The incident highlights the importance of implementing defense-in-depth strategies and proper security controls to prevent unauthorized access to sensitive server resources. Regular security updates, input validation, and access control enforcement are critical components in preventing exploitation of such vulnerabilities and maintaining overall system security posture.