CVE-2016-1000002 in gdm3
Summary
by MITRE
gdm3 3.14.2 and possibly later has an information leak before screen lock
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Analysis
by VulDB Data Team • 03/04/2025
The vulnerability identified as CVE-2016-1000002 affects the GNOME Display Manager version 3.14.2 and potentially subsequent releases, presenting a critical information disclosure issue that occurs prior to screen lock activation. This flaw resides within the gdm3 component responsible for managing graphical user sessions and display management in GNOME desktop environments. The vulnerability specifically manifests during the transition period between active user sessions and locked screen states, creating a window where sensitive information may be inadvertently exposed to unauthorized parties. The issue stems from improper handling of session data and memory management during the screen locking process, allowing potential attackers to access cached information that should remain protected until the user explicitly locks their session.
The technical implementation of this vulnerability involves a race condition or improper memory cleanup mechanism that occurs when the display manager prepares to lock the screen. During this preparation phase, session-specific data structures containing user credentials, application states, or other sensitive information may not be properly cleared or secured before the locking mechanism engages. This creates a temporal gap where an attacker with local access or specific privileges could potentially extract information from memory segments that should have been sanitized. The flaw operates at the system level within the display manager's authentication and session management subsystem, making it particularly concerning for enterprise environments where multiple users share systems or where physical access to devices is possible. The vulnerability demonstrates characteristics consistent with CWE-200 Information Exposure and may also relate to CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization.
From an operational standpoint, this information leak before screen lock can have severe implications for user privacy and system security. Attackers could potentially harvest session tokens, cached passwords, browsing history, or other sensitive data that remains accessible during the brief window before the screen locks. The impact extends beyond individual user privacy concerns to encompass potential credential theft, session hijacking, and unauthorized access to confidential information. In multi-user environments or shared computing spaces, this vulnerability could enable malicious users to access data belonging to other system users. The vulnerability's exploitation requires local access or specific privilege levels, but the potential for escalation exists when combined with other attack vectors. Organizations using GNOME desktop environments with gdm3 versions affected by this vulnerability face increased risk of unauthorized information disclosure, particularly in environments where physical security controls are insufficient or where users may leave systems unattended.
Mitigation strategies for this vulnerability involve immediate patching of affected gdm3 installations to the latest secure versions that address the information leak issue. System administrators should prioritize updating their GNOME display manager components and verify that all systems running affected versions have received security patches. Additionally, organizations should implement monitoring for unusual access patterns or unauthorized attempts to access session data during screen lock transitions. Configuration hardening measures including stricter session management policies, enhanced physical security controls, and regular security audits can help reduce the risk exposure. The vulnerability highlights the importance of proper memory management and session cleanup procedures in display managers and underscores the need for comprehensive security testing of authentication and session management components. Organizations should also consider implementing additional security controls such as automatic screen locking after periods of inactivity, enhanced user session monitoring, and regular security assessments of desktop environments to prevent similar issues from occurring in other system components.