CVE-2021-21213 in Chrome
Summary
by MITRE • 04/26/2021
Use after free in WebMIDI in Google Chrome prior to 90.0.4430.72 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 04/30/2021
The vulnerability identified as CVE-2021-21213 represents a critical use-after-free flaw in Google Chrome's WebMIDI implementation that existed prior to version 90.0.4430.72. This issue resides within the browser's handling of WebMIDI API functionality which allows web applications to communicate with MIDI devices through the browser environment. The vulnerability manifests when a malicious HTML page attempts to exploit improper memory management during MIDI object lifecycle operations, creating conditions where freed memory locations can be accessed after deallocation.
The technical exploitation of this vulnerability involves a sophisticated heap corruption attack that leverages the improper handling of reference counting and object destruction within Chrome's WebMIDI subsystem. When a web page creates and subsequently destroys MIDI objects, the memory management system fails to properly track object references, leading to situations where memory that has been freed can still be accessed by subsequent operations. This creates a classic use-after-free condition where attackers can manipulate the freed memory to execute arbitrary code or cause unexpected behavior within the browser process. The vulnerability is particularly dangerous because it operates within the browser's rendering context, potentially allowing remote code execution without user interaction.
The operational impact of CVE-2021-21213 extends beyond simple browser compromise as it represents a privilege escalation vector that can be leveraged by remote attackers to gain control over affected systems. This vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in memory management, and demonstrates how improper object lifecycle management can create persistent security risks. The attack surface is particularly concerning given that WebMIDI functionality is commonly enabled in modern browsers and can be accessed through standard web pages without requiring special permissions or user actions. This makes the vulnerability highly exploitable in real-world scenarios where users visit malicious websites, potentially leading to complete system compromise.
Security professionals should implement immediate mitigations including prompt browser updates to version 90.0.4430.72 or later, which contains the necessary patches to address the memory management issues in the WebMIDI implementation. Organizations should also consider implementing network-level protections such as web application firewalls and content filtering solutions that can detect and block malicious web content attempting to exploit this vulnerability. Additionally, browser hardening measures including sandboxing enhancements and strict content security policies can provide additional defense-in-depth layers. The vulnerability demonstrates the importance of proper memory management in browser components and aligns with ATT&CK technique T1059.001 for remote code execution through browser exploitation, emphasizing the need for continuous security auditing of browser APIs and their underlying implementations.