CVE-2007-3381 in Display Manager
Summary
by MITRE
The GDM daemon in GNOME Display Manager (GDM) before 2.14.13, 2.16.x before 2.16.7, 2.18.x before 2.18.4, and 2.19.x before 2.19.5 does not properly handle NULL return values from the g_strsplit function, which allows local users to cause a denial of service (persistent daemon crash) via a crafted command to the daemon s socket, related to (1) gdm.c and (2) gdmconfig.c in daemon/, and (3) gdmconfig.c and (4) gdmflexiserver.c in gui/.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 06/07/2025
The vulnerability described in CVE-2007-3381 represents a classic buffer overflow and null pointer dereference issue within the GNOME Display Manager daemon. This flaw exists in multiple versions of GDM across different release branches, specifically affecting versions prior to 2.14.13, 2.16.7, 2.18.4, and 2.19.5 respectively. The vulnerability stems from improper error handling within the daemon's command processing logic, where the g_strsplit function's return value is not adequately validated before subsequent processing. This function is commonly used in C applications for splitting strings into arrays of substrings, but when it returns NULL due to memory allocation failure or invalid input, the daemon fails to check this condition properly.
The technical exploitation of this vulnerability occurs through crafted commands sent to the GDM daemon's socket interface. When a local user sends specially constructed input to the daemon, the g_strsplit function fails to process the malformed data correctly and returns NULL. The daemon then attempts to use this NULL pointer in subsequent operations without proper validation, leading to a segmentation fault that causes the daemon to crash persistently. This crash results in a denial of service condition where the display manager becomes unavailable, preventing legitimate users from accessing the graphical login interface. The vulnerability affects multiple source files including gdm.c, gdmconfig.c, and gdmflexiserver.c within both the daemon and gui components of the GDM system.
From an operational impact perspective, this vulnerability creates a persistent denial of service condition that can severely disrupt system availability for graphical login sessions. The daemon crash occurs during command processing, meaning that any local user with access to the socket interface can trigger this condition repeatedly, making it particularly dangerous in multi-user environments where unauthorized users might attempt to disrupt system services. The vulnerability demonstrates a fundamental flaw in input validation and error handling practices within the GDM codebase, where the assumption that g_strsplit will always return valid data leads to unsafe memory operations. This issue falls under CWE-476 which specifically addresses NULL pointer dereference vulnerabilities, and aligns with ATT&CK technique T1499.004 which covers network disruption through service availability attacks.
The recommended mitigations for this vulnerability include immediate upgrading to patched versions of GDM that properly handle NULL return values from g_strsplit functions. System administrators should ensure that all affected GDM installations are updated to versions 2.14.13, 2.16.7, 2.18.4, or 2.19.5 respectively, depending on their current release branch. Additionally, implementing proper input validation and error handling mechanisms in daemon socket processing can provide defense-in-depth protection. Organizations should also consider restricting access to the GDM socket interface to authorized users only, as the vulnerability requires local access to trigger. The patch implementation typically involves adding explicit NULL checks after g_strsplit calls and implementing appropriate error handling routines that prevent the daemon from crashing when invalid input is received. This vulnerability highlights the importance of robust error handling in system services and demonstrates how seemingly minor input validation gaps can lead to significant availability issues in critical system components.