CVE-2020-5237 in uploader-bundle
Summary
by MITRE
oneup/uploader-bundle before 1.9.3 and 2.1.5, can be exploited to upload files to arbitrary folders on the filesystem. The assembly process can further be misused with some restrictions to delete and copy files to other locations. This is fixed in versions 1.9.3 and 2.1.5.
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Analysis
by VulDB Data Team • 05/12/2025
The vulnerability identified as CVE-2020-5237 affects the oneup/uploader-bundle PHP package, which is commonly used in web applications for handling file uploads. This issue represents a critical security flaw that allows unauthorized users to manipulate the file upload process beyond its intended scope. The vulnerability exists in versions prior to 1.9.3 and 2.1.5 of the bundle, making a significant portion of applications using this component potentially vulnerable to exploitation. The flaw stems from inadequate input validation and improper access controls within the file handling mechanism, creating opportunities for attackers to bypass normal upload restrictions and gain elevated privileges in the file system operations.
The technical implementation of this vulnerability involves a combination of path traversal and privilege escalation techniques that leverage the bundle's file management functions. Attackers can exploit the flawed validation logic to specify arbitrary directory paths during the upload process, effectively allowing them to write files to locations outside the intended upload directories. This misconfiguration creates a directory traversal condition where the application fails to properly sanitize user-supplied input that determines the destination of uploaded files. The vulnerability is further compounded by the fact that the exploitation process can be extended to perform additional file system operations including deletion and copying of existing files, which significantly increases the potential impact of the attack vector.
The operational impact of CVE-2020-5237 extends beyond simple unauthorized file uploads, as it provides attackers with the capability to manipulate the entire file system structure of the affected application. This vulnerability can be classified under CWE-22, which addresses path traversal issues, and CWE-73, which covers external control of file name or path. The potential for remote code execution increases substantially when attackers can place malicious files in critical system directories, as they can leverage the application's file processing capabilities to execute arbitrary code. The attack surface is particularly concerning because the vulnerability affects web applications that rely on file upload functionality, which is a common feature across numerous business applications including content management systems, file sharing platforms, and administrative interfaces.
The exploitation of this vulnerability aligns with several techniques documented in the MITRE ATT&CK framework, particularly under the T1059.007 technique for command and scripting interpreter and T1078.004 for valid accounts. Attackers can leverage the file upload capability to establish persistence mechanisms by placing malicious scripts or binaries in system directories, while also potentially using the file deletion and copying functions to cover their tracks or manipulate existing system files. The vulnerability's remediation requires updating to versions 1.9.3 or 2.1.5, which implement proper input validation and access control measures. Organizations should also implement additional security controls such as restricting file upload directories, implementing proper file type validation, and monitoring for unusual file system operations. The incident response implications include conducting thorough security assessments of all applications using this bundle and implementing network segmentation to limit the potential damage from successful exploitation attempts.
This vulnerability demonstrates the critical importance of proper input validation and access control in web application security. The flaw represents a failure in the principle of least privilege, where the application does not properly restrict user actions to only authorized operations. Security practitioners should consider this vulnerability as part of broader application security assessments, particularly when evaluating file handling capabilities and directory traversal protections. The remediation process involves not only updating the vulnerable component but also conducting comprehensive security reviews of all file system operations within the application to ensure no other similar vulnerabilities exist. Organizations should prioritize immediate patching of affected systems while implementing additional monitoring and logging mechanisms to detect potential exploitation attempts. The vulnerability also highlights the need for regular security assessments of third-party components and the importance of maintaining up-to-date security practices to prevent similar issues from arising in other parts of the application stack.