CVE-2020-6418 in Chrome
Summary
by MITRE
Type confusion in V8 in Google Chrome prior to 80.0.3987.122 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability identified as CVE-2020-6418 represents a critical type confusion flaw within the V8 JavaScript engine that powers Google Chrome. This vulnerability stems from improper handling of object types during runtime execution, creating a condition where the engine incorrectly interprets the data type of objects in memory. The flaw exists in the way V8 manages object transitions and type information, particularly when dealing with dynamic property assignments and object reinitialization. Attackers can exploit this by crafting malicious HTML pages that manipulate object types in unexpected ways, leading to memory corruption that can be leveraged for remote code execution.
The technical nature of this vulnerability aligns with CWE-479, which describes a condition where an application uses a type that is different from the one it expects, and maps to ATT&CK technique T1059.007 for JavaScript-based attacks. The type confusion occurs during the execution phase when the V8 engine attempts to optimize object access patterns but fails to properly validate type consistency. This creates a scenario where a pointer or memory location can be interpreted as multiple different data types, allowing attackers to manipulate memory layout and execute arbitrary code. The vulnerability specifically affects Chrome versions prior to 80.0.3987.122, indicating that this was a complex issue involving the interaction between JavaScript optimization and memory management systems.
The operational impact of CVE-2020-6418 is severe as it enables remote code execution without user interaction, making it particularly dangerous for web-based attacks. Attackers can craft HTML pages that, when loaded in Chrome, trigger the type confusion condition and subsequently corrupt heap memory. This heap corruption can lead to arbitrary code execution with the privileges of the Chrome process, potentially allowing for full system compromise. The vulnerability's exploitability is enhanced by the fact that it requires no user interaction beyond visiting a malicious website, making it particularly effective for drive-by attacks. Security researchers have noted that the exploitation techniques often involve crafting specific JavaScript code patterns that force the V8 engine into inconsistent object type states.
Mitigation strategies for CVE-2020-6418 primarily focus on immediate patching and browser updates to the affected versions. Organizations should prioritize updating Chrome to version 80.0.3987.122 or later, which includes fixes for the type confusion vulnerability in V8. Additional protective measures include implementing Content Security Policy headers to restrict script execution, enabling sandboxing features within Chrome, and utilizing browser security extensions that can detect and block suspicious JavaScript patterns. Network-level protections such as web application firewalls can also help detect and prevent exploitation attempts. The fix implemented by Google involved strengthening type validation checks within the V8 engine's optimization routines and improving the consistency of object type transitions during runtime execution, addressing the core root cause of the heap corruption vulnerability.