CVE-2020-6476 in Chrome
Summary
by MITRE
Insufficient policy enforcement in tab strip in Google Chrome prior to 83.0.4103.61 allowed an attacker who convinced a user to install a malicious extension to bypass navigation restrictions via a crafted Chrome Extension.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability identified as CVE-2020-6476 represents a critical policy enforcement flaw within Google Chrome's tab strip functionality that existed prior to version 83.0.4103.61. This issue stems from inadequate restrictions on how browser extensions can interact with user navigation controls, creating a pathway for malicious actors to circumvent intended security boundaries. The flaw specifically targets Chrome's extension architecture where tab strip operations are not properly validated against established security policies, allowing unauthorized extension behavior that should be restricted.
The technical implementation of this vulnerability exploits the trust model inherent in Chrome's extension system where certain extension permissions are granted without sufficient validation of the extension's actual behavior. When a user installs a malicious extension, the flaw allows it to manipulate tab navigation controls in ways that bypass the normal restrictions imposed by Chrome's security policies. This occurs because the tab strip component does not adequately enforce policy boundaries that should prevent extensions from altering navigation behavior in unauthorized ways. The vulnerability essentially creates a loophole where extension developers can craft malicious code that appears benign but can manipulate user navigation through the tab interface.
The operational impact of this vulnerability extends beyond simple navigation manipulation as it represents a significant escalation path for attackers seeking to compromise user browsing sessions. An attacker who successfully convinces a user to install a malicious extension can use this flaw to redirect users to malicious websites, inject unwanted content, or manipulate browser sessions in ways that bypass normal security controls. The attack vector relies on social engineering to gain initial access through extension installation, but once successful, the vulnerability allows the attacker to maintain persistent control over the user's navigation behavior. This creates a persistent threat that can be used for phishing campaigns, data exfiltration, or other malicious activities that leverage the user's trust in their browsing environment.
Mitigation strategies for CVE-2020-6476 require both immediate and long-term approaches to address the underlying policy enforcement gaps. Users should immediately update to Chrome version 83.0.4103.61 or later where the vulnerability has been patched, while administrators should implement strict extension management policies that limit which extensions can be installed on corporate devices. The fix addresses the core issue by strengthening the policy enforcement mechanisms in Chrome's tab strip component, ensuring that extension permissions are properly validated against the security boundaries that protect user navigation. Organizations should also consider implementing browser extension whitelisting policies and regular security audits to prevent installation of potentially malicious extensions that could exploit similar vulnerabilities in the future.
This vulnerability aligns with CWE-693, which addresses protection mechanism failures, specifically focusing on inadequate policy enforcement and protection mechanism bypass. The flaw demonstrates how insufficient access control validation in browser components can create security boundaries that are easily circumvented. From an ATT&CK perspective, this vulnerability maps to T1176 for Browser Extensions and T1059 for Command and Scripting Interpreter, as it enables attackers to leverage browser extension capabilities to execute malicious code. The attack chain typically begins with user interaction through social engineering, followed by extension installation, and concludes with navigation manipulation that bypasses Chrome's built-in security controls. The vulnerability highlights the importance of comprehensive security testing of browser components, particularly those that handle user interface interactions and extension permissions, to prevent similar policy enforcement failures from occurring in other browser components or security systems.