CVE-2020-6387 in Chrome
Summary
by MITRE
Out of bounds write in WebRTC in Google Chrome prior to 80.0.3987.87 allowed a remote attacker to potentially exploit heap corruption via a crafted video stream.
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability identified as CVE-2020-6387 represents a critical out-of-bounds write flaw within the WebRTC implementation of Google Chrome browser versions prior to 80.0.3987.87. This issue resides in the handling of video streams within the browser's WebRTC subsystem, which is designed to enable real-time communication directly between web browsers without requiring intermediate servers. The flaw manifests when processing specially crafted video content that triggers improper memory management during the decoding or rendering of multimedia data streams.
This vulnerability falls under the Common Weakness Enumeration category CWE-787, which specifically addresses out-of-bounds write conditions where a program writes data past the boundaries of a fixed-length buffer. The attack vector requires a remote adversary to deliver a malicious video stream to a victim who is running an affected version of Chrome. The exploitation occurs during the normal processing of WebRTC video data, making it particularly dangerous as users may encounter such content through normal browsing activities including video conferencing applications, streaming services, or malicious websites that leverage WebRTC functionality.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential pathways for remote code execution. When the out-of-bounds write occurs in heap memory, it can overwrite adjacent memory locations including function pointers, control data, or other critical program structures. This heap corruption can lead to unpredictable behavior including application crashes, data corruption, or more severely, allow attackers to execute arbitrary code with the privileges of the Chrome process. The remote nature of the attack means that victims do not need to interact with malicious content directly, as the exploit can be triggered through automated web page loading and media processing.
From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1203, which involves gaining access to execution environments through legitimate system processes. Attackers could craft malicious video streams that exploit this flaw in video conferencing applications, streaming platforms, or social media sites where WebRTC is commonly implemented. The attack surface is broad given that WebRTC is widely deployed across numerous applications and services, making this vulnerability particularly attractive for threat actors seeking to compromise large numbers of users. The exploitation requires no special user interaction beyond visiting a malicious website or participating in a video conference session, making it highly effective for mass deployment attacks.
The recommended mitigation strategy involves immediate upgrading to Chrome version 80.0.3987.87 or later, which contains the necessary patches to address the heap corruption issue. Organizations should also implement network-level controls to monitor and potentially block suspicious WebRTC traffic patterns, though this approach is less effective as the vulnerability is primarily within the browser's handling of legitimate video content. Browser vendors and security teams should also consider implementing additional sandboxing measures and memory protection mechanisms to limit the impact of similar vulnerabilities in the future, particularly given the widespread use of WebRTC in modern web applications.