CVE-2020-6380 in Chrome
Summary
by MITRE
Insufficient policy enforcement in extensions in Google Chrome prior to 79.0.3945.130 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted Chrome Extension.
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability identified as CVE-2020-6380 represents a critical flaw in Google Chrome's extension security model that existed prior to version 79.0.3945.130. This weakness stems from insufficient policy enforcement mechanisms that govern how Chrome extensions interact with the browser's site isolation features. The vulnerability specifically targets the renderer process compromise scenario where an attacker has already gained control of a browser tab or process, then exploits this access to bypass crucial security boundaries designed to isolate different websites and their respective processes. The flaw operates at the intersection of Chrome's extension architecture and its security isolation mechanisms, creating a pathway for privilege escalation and cross-site data access that should have been prevented by the browser's security model.
This technical vulnerability manifests when a compromised renderer process attempts to leverage extension capabilities to circumvent site isolation protections that are fundamental to Chrome's security architecture. The extension system in Chrome is designed to provide additional functionality while maintaining strict boundaries between different origins and processes, but this flaw allows malicious extensions to effectively ignore or override these boundaries. The attack vector specifically exploits the trust model between the browser and its extensions, where extensions are granted elevated privileges but should still be contained within the scope of their intended security boundaries. This represents a failure in Chrome's mandatory access control mechanisms that should prevent extensions from accessing resources outside their designated scope even when the underlying process has been compromised.
The operational impact of CVE-2020-6380 is significant and potentially devastating for users of affected Chrome versions. An attacker who has already compromised a renderer process can leverage this vulnerability to access data from other websites, effectively breaking the isolation that site isolation mechanisms are designed to provide. This breach allows for cross-site scripting attacks, data exfiltration, and potential information disclosure across different origins that should normally be separated. The vulnerability undermines the core security principle of process isolation that prevents one website from accessing another website's data or resources, making it particularly dangerous in environments where users visit multiple sites with varying levels of trust and security requirements. The attack scenario is especially concerning because it requires only a compromised renderer process rather than complete system compromise, making it more accessible to attackers who may have already achieved partial access through other means.
The vulnerability demonstrates a clear failure in Chrome's security architecture that aligns with CWE-693, which addresses protection mechanism design flaws, and maps to ATT&CK technique T1170 for 'Lateral Movement' through the exploitation of browser vulnerabilities. Organizations and individuals using Chrome versions prior to 79.0.3945.130 face increased risk of targeted attacks that can leverage this flaw to expand their access beyond the initial compromised process. The recommended mitigation strategy involves immediate upgrade to Chrome version 79.0.3945.130 or later, which includes fixes to the extension policy enforcement mechanisms. Additionally, administrators should implement extended monitoring for unusual extension behavior, review extension permissions, and consider temporary restriction of extension installation and execution until the upgrade is complete. Security teams should also conduct vulnerability assessments to identify any potential exploitation attempts and ensure that their incident response procedures include specific handling of browser extension-related security incidents. The fix implemented by Google addresses the core policy enforcement gap in how extensions interact with site isolation boundaries, restoring the intended security architecture that separates different origins and prevents unauthorized cross-site access.