CVE-2023-5524 in Web Companion
Summary
by MITRE • 10/25/2023
Insufficient blacklisting in M-Files Web Companion before release version 23.10 and LTS Service Release Versions before 23.8 LTS SR1 allows
Remote Code Execution
via specific file types
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Analysis
by VulDB Data Team • 02/23/2026
The vulnerability identified as CVE-2023-5524 represents a critical security flaw in M-Files Web Companion software that affects versions prior to 23.10 and LTS Service Release Versions before 23.8 LTS SR1. This vulnerability stems from insufficient blacklisting mechanisms that fail to properly restrict file types processed by the application, creating a pathway for remote code execution attacks. The flaw specifically targets the application's handling of certain file types that should be prohibited from being processed or executed within the system environment.
The technical implementation of this vulnerability occurs within the file processing pipeline of M-Files Web Companion where the application fails to maintain a comprehensive blacklist of dangerous file extensions and content types. Attackers can exploit this weakness by uploading or submitting files with specific extensions that are not properly filtered out, allowing malicious code to execute within the application context. This insufficient filtering mechanism creates a direct vector for remote code execution as the application processes these unauthorized file types without proper validation or sanitization. The vulnerability is particularly concerning because it operates at the file ingestion level where the application handles user-submitted content, making it accessible through web interfaces and remote attack surfaces.
The operational impact of CVE-2023-5524 extends beyond simple unauthorized code execution to potentially enable full system compromise and persistent access. When successfully exploited, attackers can execute arbitrary code on the target system with the privileges of the M-Files Web Companion service account, which typically has significant access rights within the application environment. This could lead to data exfiltration, system compromise, and lateral movement within the network infrastructure. The vulnerability affects organizations using M-Files document management systems, potentially exposing sensitive business documents and operational data to unauthorized access. The remote nature of the exploit means that attackers can leverage this vulnerability from external networks without requiring physical access to the target systems.
Organizations should implement immediate mitigations including upgrading to the patched versions of M-Files Web Companion where version 23.10 and 23.8 LTS SR1 or later are available. The security patch addresses the insufficient blacklisting by implementing a comprehensive file type validation mechanism that properly restricts dangerous file extensions and content types. Additionally, network administrators should consider implementing additional protective measures such as web application firewalls that can detect and block suspicious file upload patterns, and monitoring for unusual file processing activities within the M-Files environment. The vulnerability aligns with CWE-20: Improper Input Validation, which classifies this as a weakness where insufficient validation of input data allows malicious content to bypass security controls. From an ATT&CK framework perspective, this vulnerability maps to T1059.007: Command and Scripting Interpreter: Python, and T1566.001: Phishing: Spearphishing Attachment, as attackers would need to deliver malicious files through email or web interfaces to exploit the vulnerability. Organizations should also conduct thorough security assessments of their M-Files installations to ensure no other similar blacklisting deficiencies exist within their document management infrastructure.