CVE-2023-39928 in WebKitGTK
Summary
by MITRE • 10/25/2023
A use-after-free vulnerability exists in the MediaRecorder API of Webkit WebKitGTK 2.40.5. A specially crafted web page can abuse this vulnerability to cause memory corruption and potentially arbitrary code execution. A user would need to to visit a malicious webpage to trigger this vulnerability.
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Analysis
by VulDB Data Team • 09/06/2025
The vulnerability identified as CVE-2023-39928 represents a critical use-after-free flaw within the MediaRecorder API implementation of WebKit WebKitGTK version 2.40.5. This type of vulnerability occurs when a program continues to reference memory locations after they have been freed or deallocated, creating opportunities for memory corruption that can be exploited by malicious actors. The MediaRecorder API is designed to capture media streams from web applications, making it a core component in web-based multimedia functionality that handles audio and video recording operations.
The technical nature of this vulnerability stems from improper memory management within the WebKitGTK rendering engine's MediaRecorder implementation. When a web page interacts with the MediaRecorder API and subsequently triggers specific conditions, the underlying code fails to properly manage object lifecycles, leading to situations where memory that should have been released remains accessible and can be manipulated. This use-after-free condition creates a memory corruption scenario that can be leveraged by attackers to execute arbitrary code on the target system. The flaw specifically affects the WebKitGTK framework, which is commonly used in Linux desktop applications and embedded systems that rely on WebKit for web content rendering.
The operational impact of this vulnerability is significant as it enables remote code execution through web-based attacks without requiring any additional privileges or user interaction beyond visiting a malicious webpage. The attack vector is particularly dangerous because it operates entirely within the browser environment, exploiting the legitimate functionality of the MediaRecorder API to deliver malicious payloads. Users who visit compromised websites could have their systems compromised without any explicit action beyond normal web browsing activities, making this vulnerability particularly insidious in real-world scenarios where users may encounter malicious content through various online channels.
The vulnerability aligns with CWE-416, which describes the use-after-free condition, and represents a clear example of how modern web APIs can introduce security risks when proper memory management practices are not implemented. From an ATT&CK framework perspective, this vulnerability maps to techniques involving initial access through web-based exploits and privilege escalation via code execution. The attack surface is primarily through web browsers and applications that utilize WebKitGTK, affecting desktop environments, web-based applications, and embedded systems that rely on this rendering engine for multimedia functionality.
Mitigation strategies should focus on immediate patching of WebKitGTK to version 2.40.6 or later, which contains the necessary memory management fixes. Organizations should implement web content filtering and sandboxing measures to limit exposure to potentially malicious websites. Browser hardening techniques including disabling unnecessary media APIs, implementing strict content security policies, and maintaining up-to-date browser versions should be enforced. Additionally, user education regarding the risks of visiting untrusted websites and the importance of keeping software updated remains crucial in defending against this type of exploitation. Network-based protections such as web application firewalls and intrusion detection systems can help detect and block attempts to exploit this vulnerability during initial access phases.