CVE-2020-6527 in Chrome
Summary
by MITRE
Insufficient policy enforcement in CSP in Google Chrome prior to 84.0.4147.89 allowed a remote attacker to bypass content security policy via a crafted HTML page.
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Analysis
by VulDB Data Team • 05/05/2025
The vulnerability identified as CVE-2020-6527 represents a critical weakness in Google Chrome's Content Security Policy implementation that existed prior to version 84.0.4147.89. This flaw constitutes a significant bypass of Chrome's security mechanisms designed to prevent cross-site scripting attacks and other code injection vulnerabilities. The issue specifically targets the browser's Content Security Policy enforcement system, which serves as a crucial defense layer against malicious content execution. Content Security Policy acts as a security policy framework that helps prevent attacks such as cross-site scripting by controlling which resources can be loaded and executed within a web page context. When this protection mechanism fails, it creates an opening for attackers to execute unauthorized code in the victim's browser environment.
The technical nature of this vulnerability stems from insufficient policy enforcement within Chrome's Content Security Policy implementation. Attackers could craft specially designed HTML pages that would circumvent the normal security checks that should prevent execution of malicious scripts or loading of unauthorized resources. This bypass occurs at the policy enforcement level rather than the policy definition level, meaning that even properly configured CSP headers could be circumvented through carefully constructed malicious content. The flaw allows remote attackers to execute code that would normally be blocked by Content Security Policy directives, effectively neutralizing a core web security mechanism. This type of vulnerability falls under the CWE-693 category of "Protection Mechanism Failure" and represents a direct violation of the principle of least privilege in web security.
The operational impact of this vulnerability extends far beyond simple code execution, as it undermines fundamental web security assumptions that developers and security professionals rely upon. When Content Security Policy can be bypassed, it creates a cascading effect that weakens the entire security posture of web applications that depend on this protection mechanism. Organizations that implement Content Security Policy headers as part of their security strategy would find their defenses compromised, potentially allowing attackers to execute malicious scripts, steal user data, or perform other harmful actions. The vulnerability particularly affects users who visit malicious websites or are targeted through phishing campaigns that exploit this specific bypass technique. The attack surface includes any web application or service that relies on Content Security Policy for protection against code injection attacks, making it a widespread concern across the web ecosystem.
Mitigation strategies for CVE-2020-6527 focus primarily on updating to the patched version of Google Chrome, specifically version 84.0.4147.89 or later, which contains the necessary fixes to properly enforce Content Security Policy directives. Browser vendors and security teams should prioritize immediate deployment of this update across all affected systems, particularly in enterprise environments where users may be exposed to malicious content through various attack vectors. Organizations should also conduct thorough security assessments to identify any applications or services that might be vulnerable to this bypass technique, ensuring that additional security controls are implemented where necessary. Security monitoring should include detection of suspicious Content Security Policy violations or attempts to bypass security mechanisms. The vulnerability highlights the importance of maintaining up-to-date browser software and implementing layered security approaches that do not rely solely on Content Security Policy for protection. From an ATT&CK perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion, specifically targeting the T1059.007 and T1566.001 tactics that involve executing malicious code and social engineering attacks.