CVE-2020-6394 in Chrome
Summary
by MITRE
Insufficient policy enforcement in Blink in Google Chrome prior to 80.0.3987.87 allowed a remote attacker to bypass content security policy via a crafted HTML page.
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability identified as CVE-2020-6394 represents a critical weakness in Google Chrome's Blink rendering engine that persisted through versions prior to 80.0.3987.87. This flaw emerged from insufficient policy enforcement mechanisms within the browser's core rendering component, specifically affecting how content security policies were implemented and enforced. The vulnerability operates at the intersection of browser security architecture and web application protection, creating a potential attack vector that could be exploited by remote adversaries without user interaction.
The technical nature of this vulnerability stems from a failure in Blink's implementation of content security policy enforcement. Content security policy serves as a critical web application security control that helps prevent cross-site scripting attacks and other code injection vulnerabilities by defining which sources of content are allowed to be loaded and executed within a web page. The flaw allowed attackers to craft specially designed HTML pages that could bypass these security controls, effectively rendering the content security policy mechanism ineffective. This bypass occurred at the browser level rather than at the application level, making it particularly dangerous as it undermined fundamental web security assumptions.
The operational impact of this vulnerability extends beyond simple privilege escalation or data theft. Attackers could exploit this weakness to execute malicious code in contexts where they would normally be blocked by content security policies, potentially leading to full browser compromise, session hijacking, or data exfiltration. The remote nature of the attack means that users could be compromised simply by visiting a malicious website or viewing a crafted email with embedded HTML content. This vulnerability directly impacts the principle of least privilege in web browsing environments, where users expect their browsers to enforce security policies consistently. The flaw also affects the integrity of web applications that rely on content security policy as a primary defense mechanism against injection attacks.
Mitigation strategies for CVE-2020-6394 primarily focus on immediate remediation through browser updates to version 80.0.3987.87 or later, which contain the necessary patches to correct the policy enforcement implementation. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly. Additional protective measures include network-level filtering to block malicious content, enhanced browser hardening configurations, and regular security assessments of web applications to verify proper content security policy implementation. This vulnerability aligns with CWE-693, which addresses protection mechanism failures, and maps to ATT&CK technique T1059 for executing malicious code through browser-based attacks, emphasizing the need for layered security approaches that protect against both application-level and browser-level threats.