CVE-2026-42724 in CleanSkin Plugin
Summary
by MITRE • 10/10/2026
Unauthenticated Local File Inclusion in CleanSkin <= 1.5.0 versions.
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Analysis
by VulDB Data Team • 10/10/2026
The vulnerability identified as an unauthenticated local file inclusion flaw within CleanSkin versions up to and including 1.5.0 represents a critical security deficiency that allows attackers to read arbitrary files from the server's filesystem without requiring any form of authentication or user interaction. This type of vulnerability typically arises when a web application accepts unsanitized input, such as parameters passed via HTTP requests, and uses this data directly in file system operations like include statements or stream wrappers. In the context of CleanSkin, which is likely a theme or plugin for a content management system, the flaw suggests that the code fails to validate whether the requested file path exists within an expected directory structure or contains malicious characters such as null bytes or directory traversal sequences. This lack of rigorous input validation enables an attacker to manipulate the application's behavior by specifying paths outside the intended scope, thereby bypassing security controls designed to restrict access to sensitive system resources.
From a technical perspective, this vulnerability aligns with CWE-98 Improper Control of Filename for Include Statement and is often categorized under CWE-200 Exposure of Sensitive Information to an Unauthorized Actor when used to read configuration files or source code. The operational impact of such a flaw can be severe, as it allows the attacker to access sensitive data stored on the server, including database credentials, application configurations, user session tokens, and potentially proprietary source code. By reading these files, an adversary gains deep insight into the internal architecture of the web application, which can facilitate further attacks such as cross-site scripting if script tags are present in included files or remote code execution if log poisoning techniques are employed to inject malicious content into writable log files that are subsequently included by the vulnerable script. This vulnerability is frequently associated with ATT&CK technique T1083 File and Directory Discovery, where adversaries use local file inclusion as a method to enumerate and access critical system components for lateral movement or privilege escalation purposes.
The exploitation of this vulnerability does not require any user authentication, making it particularly dangerous in public-facing environments. An attacker can craft specific HTTP requests with manipulated parameters pointing to sensitive files such as /etc/passwd on Linux systems or wp-config.php in WordPress-based installations containing CleanSkin. The server processes these requests and returns the contents of the specified file directly in the response body, effectively exposing internal secrets to any internet user who discovers this vector. This exposure compromises the confidentiality integrity of the entire system hosting the application, as attackers can use the retrieved credentials to gain unauthorized access to databases or administrative panels, leading to a complete compromise of the web server and potentially the underlying operating system if further exploitation steps are taken based on the information gathered.
To mitigate this vulnerability, immediate action is required by upgrading CleanSkin to version 1.5.1 or later where the issue has been resolved through improved input validation and path canonicalization techniques. Developers should ensure that all file inclusion operations use allowlists of permitted files rather than relying solely on blacklist approaches which can be bypassed using encoding tricks or null byte injections. Implementing strict directory restrictions so that includes are confined to a specific base directory is also essential, along with disabling the display of PHP errors in production environments to prevent detailed stack traces from aiding attackers in mapping out file paths. Additionally, web application firewalls can be configured to detect and block requests containing common local file inclusion patterns such as double dots followed by slashes or null bytes within URL parameters, providing an additional layer of defense while patching is implemented across the infrastructure.