CVE-2026-63358 in FileGator
Summary
by MITRE • 07/22/2026
FileGator accepts arbitrary Unix permission values via the '/chmoditems' API endpoint and passes the value directly to PHP's native 'chmod()' function through 'octdec()' conversion, with no validation. This allows an authenticated user with 'chmod' permission to upgrade their privileges to root.
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Analysis
by VulDB Data Team • 07/22/2026
The vulnerability in FileGator presents a critical privilege escalation risk through improper input validation within the chmoditems API endpoint. This flaw exists at the intersection of inadequate access controls and unsafe file system operations, creating a pathway for authenticated users to elevate their privileges beyond intended boundaries. The system accepts arbitrary Unix permission values without proper sanitization or validation, directly passing these values to PHP's native chmod() function after conversion through octdec(). This design pattern violates fundamental security principles by trusting user input without adequate verification mechanisms.
The technical implementation of this vulnerability stems from the absence of input validation and sanitization processes within the API endpoint. When an authenticated user with chmod permissions submits malicious permission values, the system performs no checks to ensure these values conform to acceptable security parameters. The octdec() function converts the user-provided string representation of octal permissions into decimal integers, which are then passed directly to chmod() without any verification that the resulting permissions would be safe or appropriate for the target files or directories. This approach creates a direct injection vector where maliciously crafted permission values can be executed with elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to gain root-level access to the system through seemingly legitimate administrative functions. An authenticated user who already possesses chmod permissions can craft special permission values that bypass normal security boundaries and potentially grant full system control. This represents a significant compromise in the principle of least privilege, where users should only have access to resources necessary for their specific roles. The vulnerability essentially allows for arbitrary code execution through file system manipulation, enabling attackers to modify critical system files, create backdoors, or establish persistent access mechanisms.
The security implications align with CWE-20, which addresses improper input validation, and specifically relates to CWE-78, which covers OS command injection vulnerabilities. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques under T1068, where adversaries leverage legitimate administrative tools to gain higher-level permissions. The attack vector demonstrates how a seemingly minor oversight in input handling can result in catastrophic security consequences, as the vulnerability exploits the trust placed in authenticated users while failing to validate that their actions remain within acceptable security parameters. Organizations implementing FileGator must consider this vulnerability as a critical risk requiring immediate remediation through proper input validation and privilege restriction mechanisms.
Mitigation strategies should focus on implementing strict input validation for all permission values passed to chmod operations, ensuring that only predefined safe permission sets are accepted. The system must validate that submitted permissions do not exceed the current user's privileges and should reject any values that could potentially grant root or administrative access. Additionally, implementing proper logging and monitoring around chmod operations will help detect anomalous permission changes that might indicate exploitation attempts. Organizations should also consider adopting principle of least privilege enforcement, where even users with chmod permissions are restricted from setting overly permissive values such as 777 or other combinations that could lead to system compromise. Regular security audits and penetration testing should verify that no similar input validation gaps exist in other API endpoints within the application framework.