CVE-2020-12419 in Firefox
Summary
by MITRE
When processing callbacks that occurred during window flushing in the parent process, the associated window may die; causing a use-after-free condition. This could have led to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 05/05/2025
This vulnerability represents a critical use-after-free condition that emerges during the processing of callback operations within Firefox's parent process when window flushing occurs. The flaw manifests when a window associated with a callback operation terminates while the system is still processing related events, creating a scenario where freed memory locations are accessed, leading to potential memory corruption and system instability. The issue specifically impacts the browser's window management subsystem and callback handling mechanisms, which are fundamental components in the rendering and event processing pipeline.
The technical exploitation of this vulnerability stems from improper memory management during asynchronous callback execution. When a window undergoes flushing operations and subsequently dies, the system attempts to process associated callbacks that reference memory that has already been deallocated. This creates a classic use-after-free scenario where the freed memory might be reallocated for other purposes, potentially allowing an attacker to manipulate the contents of that memory location. The vulnerability is particularly concerning because it can lead to arbitrary code execution through memory corruption, making it a prime target for exploitation in browser-based attack scenarios.
The operational impact of this vulnerability extends across multiple Mozilla products including Firefox ESR versions prior to 68.10, standard Firefox versions before 78, and Thunderbird versions before 68.10.0. These affected versions represent a significant portion of deployed browser and email clients that could be exploited through malicious web content or email attachments. The vulnerability could be leveraged by attackers to execute remote code on victim systems, potentially leading to full system compromise. The nature of the flaw means that exploitation does not require user interaction beyond visiting a malicious website or opening a compromised email, making it particularly dangerous in targeted attack scenarios.
Security researchers have classified this vulnerability according to CWE-416, which specifically addresses use-after-free conditions in software systems. The vulnerability aligns with attack patterns documented in the MITRE ATT&CK framework under the technique of code injection, where adversaries exploit memory corruption vulnerabilities to execute malicious code. The affected components operate within the browser's core rendering engine and event handling system, making this a high-impact issue that could be used to bypass security controls and establish persistent access to compromised systems.
Organizations should immediately implement mitigations by upgrading to patched versions of Firefox ESR 68.10, Firefox 78, and Thunderbird 68.10.0 or later. Security teams should also consider implementing network-level protections such as content filtering and web application firewalls to prevent access to known malicious domains. Additionally, users should be educated about the risks of visiting untrusted websites and opening suspicious email attachments. The vulnerability demonstrates the importance of proper memory management in browser applications and highlights the need for comprehensive security testing of event handling and callback processing mechanisms. Regular security updates and patch management procedures should be prioritized to address similar vulnerabilities in the browser's rendering engine and asynchronous processing components.