CVE-2025-43858: Command Injection Vulnerability in YoutubeDLSharp Library

Overview

The CVE-2025-43858 vulnerability concerns YoutubeDLSharp, a wrapper for command-line video downloaders youtube-dl and yt-dlp, and its versions starting from 1.0.0-beta4 and prior to 1.1.2. This vulnerability can have severe impacts, potentially leading to system compromise or data leakage. YoutubeDLSharp is widely used for downloading videos from various platforms, and as such, this vulnerability has the potential to affect a broad range of users. The severity and broad user-base make this vulnerability a significant cybersecurity concern.

Vulnerability Summary

CVE ID: CVE-2025-43858
Severity: Critical (CVSS: 9.2)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: System compromise, potential data leakage

Affected Products

Product | Affected Versions

YoutubeDLSharp | 1.0.0-beta4 to 1.1.1

How the Exploit Works

The CVE-2025-43858 vulnerability exploits an unsafe conversion of arguments in YoutubeDLSharp. The vulnerability allows an attacker to inject malicious commands when starting `yt-dlp` from a command prompt running on Windows OS with the `UseWindowsEncodingWorkaround` value defined to true. This value is true by default, and cannot be disabled from the built-in methods from the YoutubeDL.cs file.

Conceptual Example Code

An attacker may exploit this vulnerability by injecting a malicious command into the arguments that are passed to the `yt-dlp` command, as shown in this conceptual example:

yt-dlp --extract-audio --audio-format mp3 '<malicious command>'

In this example, `` would be replaced with a command that the attacker wants to execute on the victim’s system. It’s important to note that this is a conceptual example and the actual exploit may involve more complex command injection techniques.

Mitigation Guidance

The recommended mitigation strategy for CVE-2025-43858 is to apply the vendor patch, which is available in version 1.1.2 of YoutubeDLSharp. As a temporary measure, users can also utilize a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to detect and prevent exploitation attempts. Furthermore, users should consider restricting access to the command prompt and limiting the privileges of users who can execute commands to mitigate the potential impact of this vulnerability.