CVE-2026-123095 in mpv
Summary
by MITRE • 11/05/2026
mpv 0.29.0 before 0.42.0 contains a playlist injection vulnerability in the bundled ytdl_hook script that allows remote attackers to add unchecked entries by embedding newlines in playlist URLs. Attackers controlling a feed or page can bypass url_is_safe() to open file:// or av:// inputs, reading local files or loading shared objects via ladspa for code execution.
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Analysis
by VulDB Data Team • 11/05/2026
The vulnerability identified in mpv versions prior to 0.42.0 represents a critical security flaw within the bundled ytdl_hook script, which is responsible for handling external media sources such as those provided by YouTube-dl or yt-dlp. This issue stems from an improper validation of input data when processing playlist URLs. Specifically, the application fails to adequately sanitize newline characters embedded within these URLs before they are processed further down the execution pipeline. In many web-based and multimedia applications, newlines in URL parameters can be exploited to inject additional commands or arguments into underlying system calls or configuration parsers. In this specific context, the presence of unescaped newlines allows an attacker to manipulate how the media player interprets subsequent entries within a playlist structure, effectively breaking out of the intended scope of the original request and injecting arbitrary content that bypasses existing security checks.
The core technical flaw lies in the failure of the url_is_safe() function to properly account for these injected newline characters when evaluating the legitimacy of input sources. This function is designed to restrict access to potentially dangerous protocols or local file paths, ensuring that only safe remote URLs are processed by the media player's external hook mechanisms. However, because the newline character acts as a delimiter in many parsing contexts, an attacker can craft a malicious playlist URL where one line contains a seemingly benign entry and subsequent lines contain hidden payloads. The parser processes these injected entries separately from the initial validation check, allowing them to slip past the url_is_safe() barrier without triggering alerts or rejection mechanisms. This bypass is particularly dangerous because it exploits the structural assumptions of how playlists are parsed, treating each newline-separated item as a distinct entity that may not undergo the same rigorous scrutiny as the primary URL input.
The operational impact of this vulnerability is severe, enabling remote attackers to achieve arbitrary code execution on affected systems through multiple vectors. By bypassing the safety checks, an attacker can force mpv to load local files using file:// URIs, which facilitates unauthorized access to sensitive data stored on the victim's machine. More critically, the flaw allows for the loading of shared object libraries via LADSPA (Linux Audio Developer’s Simple Plugin API) inputs. Since LADSPA plugins are dynamic libraries that can contain executable code, an attacker who controls a media feed or webpage hosting such playlists can direct mpv to load maliciously crafted .so files from local directories where write permissions exist or through other exploitation techniques. This mechanism effectively transforms the media player into a vehicle for arbitrary command execution, granting the attacker full control over the user's environment under the privileges of the running process.
From an industry standard perspective, this vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection) and CWE-20 Improper Input Validation. The failure to sanitize special characters like newlines in URL parameters is a classic example of input validation weakness that leads to code injection scenarios. Furthermore, the exploitation technique involving the loading of shared libraries for remote code execution maps directly to MITRE ATT&CK techniques such as T1059 Command and Scripting Interpreter or potentially T1204 User Execution if social engineering is involved in getting a user to open a malicious playlist file. The ability to bypass security filters like url_is_safe() also highlights issues related to CWE-78 Improper Neutralization of Special Elements used in an OS Command, although the primary vector here is more closely tied to application-level logic flaws rather than direct shell injection.
Mitigation for this vulnerability requires immediate action by users and administrators relying on affected versions of mpv. The most effective remediation strategy is to upgrade the media player software to version 0.42.0 or later, where the developers have addressed these input validation gaps within the ytdl_hook script. Until an update can be applied, users should exercise extreme caution when playing playlists sourced from untrusted third-party feeds or web pages that utilize external hooks for video playback. Disabling the use of external scripts and hooks in mpv configuration files provides a robust defensive measure by removing the attack surface entirely. Additionally, implementing strict content security policies on any internal services hosting media playlists can help prevent the distribution of maliciously crafted URLs containing embedded newlines or other control characters designed to exploit parsing logic flaws.