Description

ClipBucket V5's web installer fails to properly validate or escape the php_cli_filepath parameter before passing it to shell execution. Unauthenticated attackers can submit a crafted POST request to the installer with a malicious php_cli_filepath value to execute arbitrary commands as the web server user.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-08-25T23:17:59.860Z",
  "pubdate": "2026-08-25T23:17:59.860Z",
  "executiveSummary": "ClipBucket V5 contains a critical OS command injection vulnerability within its web installer component.\nThe vulnerability arises from the improper validation and sanitization of the 'php_cli_filepath' parameter during the installation process.\nThis flaw allows an unauthenticated remote attacker to execute arbitrary system commands with the privileges of the web server user.\nThe attack vector involves sending a specially crafted HTTP POST request to the installation interface, injecting malicious shell commands into the vulnerable parameter.\nSuccessful exploitation grants the attacker full control over the application environment and potentially the underlying host server.\nGiven the nature of the installer's execution context, this represents a severe security risk, potentially leading to unauthorized data access, system compromise, or complete service disruption.\nNo authentication is required to initiate the attack, as the installer interface is often exposed publicly before initial configuration is completed.",
  "technicalDetails": "The vulnerability is classified as an OS Command Injection, occurring within the ClipBucket V5 web installer script.\nThe root cause is the insecure handling of user-supplied input via the 'php_cli_filepath' parameter. The application fails to perform adequate input validation, filtering, or shell escaping before passing this input to a system shell execution function.\nWhen the installer processes the request, the contents of the 'php_cli_filepath' variable are directly concatenated into a command string executed by the server-side backend.\nAn attacker can exploit this by injecting shell metacharacters (such as ;, &, |, or $()) into the parameter, allowing them to chain additional commands to the intended operation.\nThe attack flow begins with the attacker locating the installer endpoint. By sending a malicious POST request to the installer, the attacker provides a crafted value for 'php_cli_filepath' designed to execute arbitrary code, such as 'php_cli_filepath=/tmp/test; id;'.\nUpon receipt, the server interprets the semicolon as a command separator, causing the system to execute both the legitimate path configuration logic and the attacker-injected 'id' command.\nThis vulnerability is particularly critical because it bypasses standard web application authentication layers, as the installer is typically designed to function before a database or user accounts are initialized.\nThe impact is significant: an attacker gains the ability to run any command permitted by the web server's system user. This includes executing reverse shells, exfiltrating configuration files containing database credentials, installing persistent backdoors, or pivoting further into the internal network infrastructure.\nBecause the execution context is the web server process, any files, directories, or system resources accessible to that user are at risk of unauthorized manipulation or exposure."
}