CVE-2018-19937 in VLC Media Player
Summary
by MITRE
A local, authenticated attacker can bypass the passcode in the VideoLAN VLC media player app before 3.1.5 for iOS by opening a URL and turning the phone.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability identified as CVE-2018-19937 represents a critical security flaw in the VideoLAN VLC media player application for iOS devices. This issue affects versions prior to 3.1.5 and constitutes a local privilege escalation vulnerability that allows authenticated attackers to bypass the application's passcode protection mechanism. The flaw specifically targets the iOS implementation of the VLC media player, which is widely used for multimedia playback across Apple mobile devices. The vulnerability arises from insufficient validation of user authentication states during specific operational conditions within the application's interface.
The technical implementation of this vulnerability stems from the application's failure to properly enforce passcode requirements when handling URL-based media playback scenarios. When an authenticated user opens a malicious URL through the VLC application and subsequently turns the phone's display off and on, the application incorrectly maintains access to protected media content without requiring passcode verification. This behavior demonstrates a fundamental flaw in the application's session management and authentication state handling. The vulnerability is classified under CWE-287, which addresses improper authentication mechanisms, and specifically relates to CWE-305, which deals with authentication bypass through multiple authentication factors.
The operational impact of this vulnerability extends beyond simple unauthorized access to media files. Attackers can exploit this weakness to gain access to protected content that users believe is secured by passcode protection, potentially including personal media, private recordings, or corporate data. The attack vector requires local authentication and involves physical interaction with the device, making it particularly concerning for users who rely on passcode protection for privacy. This vulnerability effectively undermines the security model of the iOS application, allowing attackers to bypass the intended authentication mechanisms without requiring additional privileges or network access.
Security researchers have documented that this vulnerability aligns with ATT&CK technique T1548.002, which covers bypassing user account control through manipulation of application permissions. The flaw represents a failure in the application's security architecture and demonstrates how mobile applications can inadvertently create security holes through improper handling of device state transitions. The vulnerability is particularly concerning in enterprise environments where users may store sensitive information within the VLC application, as it provides a means for unauthorized access to protected content through simple device manipulation. The issue highlights the importance of proper authentication state management in mobile applications and the need for comprehensive security testing of all application interfaces.
Mitigation strategies for this vulnerability include immediate upgrading to VLC media player version 3.1.5 or later, which contains the necessary patches to address the authentication bypass flaw. Users should also consider implementing additional security measures such as device encryption, regular application updates, and monitoring for suspicious application behavior. Organizations should ensure that mobile device management policies include requirements for keeping applications updated and should conduct regular security assessments of mobile applications used within their environments. The vulnerability serves as a reminder of the critical importance of proper authentication handling in mobile applications and the necessity of thorough security testing across all application interfaces and device state transitions.