CVE-2026-14947 in FDS
Summary
by MITRE • 08/20/2026
A high-privileged remote attacker can upload malicious ZIP archive containing directory traversal sequences such as ../ can escape the intended extraction directory and write files to arbitrary locations on the server, potentially achieve arbitrary code execution due to improper validation of archive entry paths before writing files to disk which could result in full system compromise.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability described constitutes a critical security flaw rooted in inadequate input validation during the processing of uploaded ZIP archives. This specific weakness allows an attacker with high privileges, such as those possessing administrative access or elevated user rights within the application context, to manipulate archive entry paths using directory traversal sequences like ../. When the system processes these archives, it fails to properly sanitize or canonicalize the file names contained within the compressed data before attempting to extract them to the server's filesystem. This lack of rigorous path validation creates a direct pathway for an attacker to break out of the designated upload or extraction directory and write files to arbitrary locations on the underlying operating system.
From a technical perspective, this flaw is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The core issue lies in the application's logic which trusts user-supplied data without verifying that the resolved absolute path remains within an expected boundary. By embedding relative path traversal characters into filenames inside a ZIP file, the attacker exploits the operating system's standard directory navigation mechanisms. When the extraction routine resolves these paths, it interprets ../ as moving up one level in the directory hierarchy. If this check is bypassed or ignored, files can be written to sensitive directories such as web roots, configuration folders, or even executable program directories, depending on the permissions of the process running the application.
The operational impact of this vulnerability is severe and potentially catastrophic for system integrity. The primary consequence is arbitrary code execution. If an attacker successfully writes a malicious script, shell file, or compiled binary to a location that is executed by the server or accessible via web requests, they can gain full control over the affected system. This could lead to unauthorized access to sensitive data, modification of critical application configurations, installation of backdoors for persistent access, and use of the compromised host as a pivot point for further attacks against internal network resources. In environments where high-privileged accounts are targeted, this vulnerability effectively results in complete system compromise, undermining all other security controls that rely on user isolation or privilege separation.
This type of attack aligns with several tactics defined in the MITRE ATT&CK framework. It is closely associated with Tactic TA0004: Privilege Escalation and Technique T1505.002: Web Shell, as attackers often deploy web shells to maintain access after exploiting file upload vulnerabilities. Additionally, it relates to Tactic TA0003: Persistence if the attacker writes files that ensure continued execution upon system restarts or service reloads. The exploitation vector is remote but requires authentication, placing it within the context of authenticated attacks where trust boundaries are mismanaged.
To mitigate this vulnerability, developers must implement strict input validation and path canonicalization techniques for all file operations involving user-supplied data. One effective approach is to resolve the full absolute path of both the intended extraction directory and each entry in the archive before writing any files. The application should then verify that the resolved path of every extracted file starts with the expected base directory prefix. If a traversal sequence causes the resolved path to deviate from this allowed root, the operation must be rejected immediately. Additionally, using secure libraries or APIs designed specifically for handling archives can help ensure that internal mechanisms properly handle path normalization and prevent such escapes.
Beyond code-level fixes, defense-in-depth strategies should be employed to limit the blast radius of any potential exploitation. Running the application with least-privilege principles is essential; the process responsible for file uploads should operate under a restricted user account that lacks write permissions outside its designated working directory. Furthermore, implementing strict allow-lists for permitted file extensions and content types can prevent the upload of executable scripts or binaries even if they are successfully written to disk. Regular security audits and static code analysis tools configured to detect CWE-22 patterns can also help identify similar flaws in other parts of the application before deployment.