CVE-2019-9633 in glib
Summary
by MITRE
gio/gsocketclient.c in GNOME GLib 2.59.2 does not ensure that a parent GTask remains alive during the execution of a connection-attempting enumeration, which allows remote attackers to cause a denial of service (g_socket_client_connected_callback mishandling and application crash) via a crafted web site, as demonstrated by GNOME Web (aka Epiphany).
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Analysis
by VulDB Data Team • 07/31/2023
The vulnerability identified as CVE-2019-9633 resides within the GNOME GLib library version 2.59.2, specifically in the gio/gsocketclient.c component that handles socket client operations. This flaw represents a critical race condition and memory management issue that affects applications leveraging GLib's asynchronous networking capabilities. The vulnerability manifests when processing network connection attempts through the GTask framework, where the parent task object may be prematurely destroyed or become inaccessible during the asynchronous execution of connection operations, leading to undefined behavior and potential application instability.
The technical root cause stems from improper reference counting and lifecycle management within the GSocketClient implementation. During asynchronous connection attempts, the system fails to maintain proper ownership semantics between the parent GTask and its associated callback handlers. When a web application or browser such as GNOME Web (Epiphany) attempts to establish network connections, the callback function g_socket_client_connected_callback executes without ensuring that the parent task object remains valid throughout the operation. This creates a window where the task object can be freed or invalidated by concurrent operations while the callback is still executing, resulting in memory corruption and application crashes.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more sophisticated attack vectors. Remote attackers can craft malicious web content that triggers multiple concurrent connection attempts, exploiting the race condition to force application crashes and prevent normal operation of network-dependent applications. This vulnerability affects not only GNOME Web but any application built on GLib that utilizes asynchronous socket operations, making it particularly concerning for desktop environments and web browsers that rely heavily on the GLib networking stack. The flaw demonstrates poor adherence to memory safety principles and can be classified under CWE-129, which addresses insufficient validation of the length of input data, and CWE-125, which covers out-of-bounds read conditions.
Mitigation strategies for this vulnerability require immediate patching of affected GLib versions to the latest stable releases where the race condition has been addressed through proper reference counting mechanisms and task lifecycle management. System administrators should prioritize updating all GNOME desktop environments and applications that depend on GLib 2.59.2 or earlier versions. Additionally, developers implementing applications using GLib should review their asynchronous networking code for proper task object management and consider implementing additional safeguards against premature task destruction. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates the importance of proper asynchronous programming practices in preventing memory safety issues that can be exploited remotely. Organizations should also implement monitoring for unusual application crash patterns that might indicate exploitation attempts.