CVE-2023-4574 in Thunderbird
Summary
by MITRE • 09/11/2023
When creating a callback over IPC for showing the Color Picker window, multiple of the same callbacks could have been created at a time and eventually all simultaneously destroyed as soon as one of the callbacks finished. This could have led to a use-after-free causing a potentially exploitable crash. This vulnerability affects Firefox < 117, Firefox ESR < 102.15, Firefox ESR < 115.2, and Thunderbird < 115.2.
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Analysis
by VulDB Data Team • 06/20/2025
This vulnerability resides in the inter-process communication mechanisms of Mozilla Firefox and Thunderbird applications, specifically within the color picker window callback system. The flaw manifests when multiple identical callback objects are instantiated simultaneously during IPC operations, creating a dangerous race condition scenario. The technical implementation involves improper memory management where duplicate callback references are created without adequate synchronization mechanisms to prevent concurrent access patterns. This design oversight creates a scenario where the system maintains multiple references to the same callback object, leading to a complex memory state where destruction operations occur simultaneously across multiple references.
The core technical flaw represents a classic use-after-free vulnerability that operates through improper object lifecycle management within the browser's IPC subsystem. When the callback objects are eventually destroyed, the system attempts to free memory that may have already been deallocated by another concurrent destruction operation. This memory corruption occurs because the system fails to maintain proper reference counting or locking mechanisms to prevent simultaneous destruction of the same memory segments. The vulnerability specifically affects the color picker window functionality where callbacks are registered for UI events, creating a window of opportunity for exploitation during the callback creation and destruction phases.
The operational impact of this vulnerability extends beyond simple application instability to potentially enabling remote code execution in the context of the affected applications. Attackers could exploit this condition by crafting malicious web content or IPC messages that trigger the specific race condition involving callback creation and destruction. The timing aspect of this vulnerability means that exploitation requires precise control over the sequence of callback operations, making it moderately challenging to exploit in the wild but still potentially dangerous given the privileges of the browser process. The crash conditions could be leveraged to execute arbitrary code through memory corruption techniques, particularly when combined with other vulnerabilities or through advanced exploitation methods targeting the browser's memory management subsystem.
Mitigation strategies should focus on implementing proper reference counting mechanisms and synchronization primitives to prevent concurrent callback destruction operations. The fix involves modifying the callback registration system to ensure that duplicate callback objects are properly identified and managed through atomic operations or mutex locks. Security patches should address the underlying race condition by implementing proper object lifecycle management that prevents multiple simultaneous destruction operations. Organizations should prioritize updating to the patched versions of Firefox 117, Firefox ESR 102.15, Firefox ESR 115.2, and Thunderbird 115.2, as these releases contain the necessary fixes to prevent the use-after-free condition. The vulnerability aligns with CWE-415 and CWE-416 categories related to double free and use after free conditions, and could potentially map to ATT&CK techniques involving privilege escalation and code execution through memory corruption vulnerabilities.