CVE-2026-85696 in SadTalker
Summary
by MITRE • 09/04/2026
SadTalker contains an OS command injection vulnerability in the video muxing process where uploaded audio filenames are interpolated into ffmpeg commands without proper escaping. Attackers can upload audio files with shell metacharacters in the filename to break out of quoted arguments and execute arbitrary system commands when video generation occurs.
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Analysis
by VulDB Data Team • 09/04/2026
SadTalker, a widely used open-source tool for generating talking head videos from static images and audio inputs, contains a critical operating system command injection vulnerability within its video muxing subsystem. This flaw arises specifically during the process where uploaded audio files are processed to be combined with generated visual content using FFmpeg, a standard multimedia framework. The core technical deficiency lies in how the application constructs shell commands for this operation. Instead of utilizing safe programmatic interfaces or properly sanitizing user-supplied input, SadTalker directly interpolates the filename provided by the uploader into an FFmpeg command string that is subsequently executed via a system shell interface such as Python's subprocess module with shell=True or similar mechanisms. This architectural choice creates a direct pathway for malicious actors to inject arbitrary operating system commands if they can control any part of the input data, specifically the audio file name in this context.
The operational mechanism of this vulnerability relies on the lack of proper escaping and validation applied to filenames before their inclusion in shell commands. When an attacker uploads an audio file with a specially crafted filename containing shell metacharacters such as semicolons, pipes, ampersands, or backticks, these characters are interpreted by the underlying operating system's command interpreter rather than being treated as literal parts of the file path. For instance, if the application constructs a command like ffmpeg -i "uploaded_audio.wav" output.mp4 and the filename is actually audio;rm -rf /;.wav, the shell will execute the rm command after processing the initial FFmpeg invocation. This allows for arbitrary code execution with the privileges under which the SadTalker service or process is running. In many deployment scenarios, this could mean full control over the host system, leading to data exfiltration, installation of backdoors, pivoting to other network assets, or complete denial of service through resource exhaustion or destructive commands.
From a classification perspective, this vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The root cause is the failure to neutralize special elements that have significance within a particular context, specifically shell metacharacters. In terms of offensive security frameworks, this technique corresponds to ATT&CK T1059 Command and Scripting Interpreter sub-techniques such as Unix Shell or Windows CMD, where attackers leverage native system tools to execute malicious payloads. The impact extends beyond simple command execution; it represents a severe compromise of the integrity and availability of the hosting environment. If SadTalker is deployed in a cloud-based inference service or an internal tool accessible by multiple users, this vulnerability could be exploited remotely without authentication if file upload functionality is exposed publicly, making it particularly dangerous for SaaS providers offering AI-driven video generation services.
Mitigation strategies must focus on eliminating the direct use of shell interpreters when executing external programs and enforcing strict input validation. The most effective remediation involves refactoring the code to avoid passing user-supplied filenames directly into shell commands. Developers should utilize libraries or functions that execute binaries without invoking a shell, such as using execve in C-based environments or subprocess.run with list arguments in Python instead of string concatenation combined with shell=True. If shell execution is absolutely necessary due to legacy constraints, rigorous input sanitization must be implemented. This includes whitelisting allowed characters for filenames, rejecting any input containing spaces, quotes, semicolons, pipes, ampersands, backticks, dollar signs, or other special symbols that have meaning in command-line interfaces. Additionally implementing strict file type validation and storing uploaded files with randomized, system-generated names rather than retaining the original user-provided filename can significantly reduce the attack surface by decoupling user input from executable paths entirely.