CVE-2020-6474 in Chrome
Summary
by MITRE
Use after free in Blink in Google Chrome prior to 83.0.4103.61 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability identified as CVE-2020-6474 represents a critical use-after-free condition within the Blink rendering engine of Google Chrome, affecting versions prior to 83.0.4103.61. This flaw exists in the browser's handling of HTML content and specifically impacts how the engine manages memory allocation and deallocation for objects within the heap. The vulnerability arises from improper memory management practices where a pointer continues to reference memory that has already been freed, creating a dangerous state that can be exploited by malicious actors. The issue is particularly concerning because it occurs during the normal processing of web content, making it accessible through standard web browsing activities without requiring any special privileges or user interaction beyond visiting a malicious website.
The technical implementation of this vulnerability involves the Blink engine's object lifecycle management where certain DOM objects are prematurely deallocated while still being referenced by other components within the rendering pipeline. When a crafted HTML page triggers specific conditions during page rendering, the engine attempts to access memory locations that have already been released back to the heap. This use-after-free scenario creates a predictable memory corruption pattern that can be leveraged to execute arbitrary code on the target system. The flaw demonstrates poor memory safety practices and highlights the complexity of managing object references in modern browser engines where multiple components must coordinate their memory usage while maintaining security boundaries.
From an operational impact perspective, this vulnerability enables remote code execution capabilities that could allow attackers to gain complete control over affected systems. The exploitation requires only a malicious website that loads a specially crafted HTML page, making it highly dangerous for general web browsing scenarios. Attackers could potentially use this vulnerability to install malware, steal user credentials, access sensitive data, or establish persistent backdoors on compromised systems. The vulnerability affects all operating systems where the affected Chrome versions are deployed, including Windows, macOS, Linux, and mobile platforms, amplifying its potential impact across diverse threat surfaces. The remote nature of the attack means that users do not need to interact with malicious content directly, as simply visiting a compromised website could trigger the exploitation sequence.
Security researchers have classified this vulnerability under CWE-416, which specifically addresses the use of freed memory condition in software applications. The vulnerability aligns with several techniques documented in the MITRE ATT&CK framework, particularly those related to initial access through malicious websites and privilege escalation via code execution. Organizations should prioritize immediate patching of affected Chrome versions to mitigate this risk, as the vulnerability can be exploited without user interaction and provides attackers with full system compromise capabilities. The remediation process requires updating to Chrome version 83.0.4103.61 or later, which includes memory management fixes that prevent the premature deallocation of objects during HTML processing. Additionally, security teams should implement network monitoring to detect potential exploitation attempts and consider browser hardening measures such as sandboxing and content security policies to reduce the attack surface and limit the potential damage from successful exploitation attempts.