CVE-2024-39686 in Bert-VITS2
Summary
by MITRE • 07/22/2024
Bert-VITS2 is the VITS2 Backbone with multilingual bert. User input supplied to the data_dir variable is used directly in a command executed with subprocess.run(cmd, shell=True) in the bert_gen function, which leads to arbitrary command execution. This affects fishaudio/Bert-VITS2 2.3 and earlier.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 09/12/2024
The vulnerability identified as CVE-2024-39686 resides within the Bert-VITS2 framework, a multilingual text-to-speech system built upon the VITS2 architecture and enhanced with BERT embeddings for improved linguistic understanding. This system serves as a backbone for generating speech from text in multiple languages, making it a critical component in various AI-powered applications. The flaw manifests in the bert_gen function where user-provided input is directly incorporated into a command string that gets executed through subprocess.run() with shell=True parameter, creating a severe security risk that can be exploited by malicious actors to execute arbitrary commands on the system running the application.
The technical implementation of this vulnerability stems from improper input validation and sanitization practices within the data_dir parameter handling. When user input is passed directly into shell commands without proper escaping or sanitization, it creates a classic command injection vulnerability that falls under the CWE-78 category for OS Command Injection. The use of shell=True in subprocess.run() amplifies the risk by allowing shell metacharacters to be interpreted and executed, enabling attackers to chain commands, manipulate the file system, or even escalate privileges depending on the execution context. This vulnerability is particularly dangerous because it operates at the system level where the application has the permissions of the user running the Bert-VITS2 process, potentially allowing complete system compromise if the application runs with elevated privileges.
The operational impact of CVE-2024-39686 extends beyond simple command execution, as it represents a critical security weakness that could enable attackers to gain unauthorized access to systems processing speech synthesis tasks. In environments where Bert-VITS2 is deployed for production use, such as enterprise voice applications or automated customer service systems, this vulnerability could allow adversaries to extract sensitive data, install backdoors, or disrupt services entirely. The attack surface is particularly concerning given that the vulnerability affects version 2.3 and earlier of the fishaudio/Bert-VITS2 framework, suggesting that numerous deployments across various organizations might be exposed to this risk. The vulnerability also aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, where adversaries use legitimate system tools to execute malicious commands, making detection more challenging.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements. The primary fix involves eliminating the shell=True parameter and implementing proper input validation and sanitization for the data_dir variable before it enters any command execution context. Developers should employ parameterized command execution rather than string concatenation, ensuring that user input is treated as data rather than executable code. Additionally, implementing proper input length limits, character validation, and sanitization routines can prevent malicious payloads from being processed. Organizations should also consider implementing application-level firewalls or web application firewalls to monitor and filter potentially malicious inputs. The vulnerability highlights the importance of following secure coding practices as outlined in OWASP Top Ten and NIST guidelines for preventing command injection attacks, emphasizing the need for defense in depth approaches that combine multiple security controls to protect against similar vulnerabilities in other components of the system.