CVE-2026-4337 in PuMuKIT
Summary
by MITRE • 10/27/2026
Unrestricted Upload of File with Dangerous Type vulnerability in the PuMuKIT application allows a unauthenticated user to upload any type of file to the server, and to any path where the web server user has write permissions. This could also allow them to delete files.
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Analysis
by VulDB Data Team • 10/27/2026
The identified vulnerability represents a critical failure in input validation within the PuMuKIT application, specifically categorized under Unrestricted Upload of File with Dangerous Type as defined by CWE-434 and mapped to the ATT&CK technique T1505.008 for Server Software Component Injection. This flaw stems from an insufficient verification mechanism that fails to enforce strict constraints on file extensions, MIME types, or content signatures during the upload process. Consequently, an unauthenticated attacker can bypass standard security controls by submitting files containing malicious payloads rather than legitimate media assets expected by the application logic.
The technical severity of this vulnerability is compounded by the lack of path validation and access control restrictions regarding where uploaded files are stored. The system permits writing to any directory accessible by the web server user, which often includes directories with execute permissions or those directly served to end-users. This architectural weakness allows an attacker not only to upload arbitrary file types but also to place them in locations that facilitate immediate execution or remote code execution. By exploiting this unrestricted write capability, an adversary can deploy web shells, backdoors, or other executable scripts into the server's document root or temporary directories.
The operational impact of this vulnerability is severe and potentially catastrophic for system integrity. Once a malicious file is successfully uploaded to an accessible path, it can be executed by the attacker through direct HTTP requests, leading to full compromise of the underlying operating system. Furthermore, the ability to delete files introduces additional risks such as denial of service or data destruction, which undermines availability and trust in the application's reliability. The combination of arbitrary file upload with unrestricted write permissions creates a high-severity attack vector that requires immediate remediation to prevent unauthorized access and potential lateral movement within the network infrastructure.
To mitigate this vulnerability, developers must implement strict allow-listing for permitted file extensions rather than relying on deny lists or client-side validation which can be easily bypassed. It is essential to validate both the MIME type reported by the client and the actual content signature of the uploaded file using server-side libraries that inspect binary headers. Additionally, files should be stored in a directory outside the web root with no execute permissions enabled for the web service account. Implementing randomization for filenames can further prevent predictable path traversal attacks. Regular security audits and integration of static application security testing tools into the development pipeline are recommended to detect such flaws early in the software lifecycle.