CVE-2020-6393 in Chrome
Summary
by MITRE
Insufficient policy enforcement in Blink in Google Chrome prior to 80.0.3987.87 allowed a remote attacker to leak cross-origin data via a crafted HTML page.
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability identified as CVE-2020-6393 represents a critical security flaw in the Blink rendering engine that powers Google Chrome and other Chromium-based browsers. This issue stems from insufficient policy enforcement mechanisms that govern cross-origin data access, creating a pathway for remote attackers to exploit browser security boundaries. The vulnerability specifically affects Chrome versions prior to 80.0.3987.87, where the browser's security model failed to properly enforce restrictions on data access between different origins, potentially allowing malicious actors to bypass fundamental web security principles.
The technical nature of this vulnerability involves the exploitation of cross-origin resource sharing (CORS) policies and same-origin policy enforcement within the Blink engine. Attackers could craft malicious HTML pages that leverage browser inconsistencies in how they handle cross-origin data requests and responses. The flaw essentially allows unauthorized data leakage between different domains, potentially exposing sensitive information from one origin to another. This type of vulnerability directly violates core web security principles that prevent malicious websites from accessing data from other domains without proper authorization, making it particularly dangerous in the context of modern web applications where multiple domains and services interact.
The operational impact of CVE-2020-6393 extends beyond simple data leakage, as it represents a significant weakening of the browser's security sandbox that could enable more sophisticated attacks. Remote attackers could potentially aggregate leaked information to reconstruct user profiles, access session tokens, or extract sensitive business data from cross-origin resources. The vulnerability's exploitation requires a crafted HTML page delivered remotely, making it particularly dangerous in phishing campaigns or compromised websites. Security researchers have classified this issue as a remote code execution vector in certain contexts, as the leaked data could be used to facilitate further attacks or provide attackers with information needed to compromise other systems.
Mitigation strategies for this vulnerability primarily focus on immediate browser updates to versions 80.0.3987.87 and later, where Google implemented enhanced policy enforcement mechanisms. Organizations should also deploy network-based protections such as content security policies and web application firewalls to monitor and block suspicious cross-origin requests. The vulnerability aligns with CWE-284, which describes inadequate access control mechanisms, and maps to ATT&CK technique T1071.004 for application layer protocol usage. Additional defensive measures include implementing strict browser security policies, monitoring for unusual cross-origin behavior, and conducting regular security assessments of web applications that rely on browser-based functionality. Security teams should also consider deploying browser isolation solutions and monitoring for indicators of compromise related to cross-origin data leakage activities.
The remediation process involves not only updating browser versions but also ensuring that all dependent applications and services have proper cross-origin resource sharing configurations. Organizations should review their existing security policies and implement additional layers of protection to prevent similar vulnerabilities from being exploited in their environments. This includes regular security audits of web applications, implementation of proper input validation, and ensuring that all cross-origin requests are properly authenticated and authorized. The vulnerability serves as a reminder of the importance of maintaining up-to-date security configurations and the critical need for continuous monitoring of browser security patches and updates to prevent exploitation of known vulnerabilities.