CVE-2020-6491 in Chrome
Summary
by MITRE
Insufficient data validation in site information in Google Chrome prior to 83.0.4103.61 allowed a remote attacker to spoof security UI via a crafted domain name.
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Analysis
by VulDB Data Team • 05/05/2025
The vulnerability identified as CVE-2020-6491 represents a critical flaw in Google Chrome's handling of site information and security user interface elements. This issue stems from insufficient data validation mechanisms that process domain names within the browser's security context. The vulnerability affects Chrome versions prior to 83.0.4103.61 and allows remote attackers to manipulate the browser's security indicators through carefully crafted domain names. The flaw specifically targets the browser's visual security warnings and trust indicators that users rely upon to identify legitimate websites versus potentially malicious ones.
The technical implementation of this vulnerability involves the browser's failure to properly validate and sanitize domain name inputs before displaying security UI elements. When a user navigates to a maliciously crafted domain, the browser's insufficient validation allows attackers to construct domain names that can deceive the security interface. This manipulation can cause the browser to display misleading security warnings or suppress legitimate security indicators. The vulnerability leverages the way Chrome processes Internationalized Domain Names (IDN) and punycode encoding, where attackers can create domain names that appear visually similar to legitimate sites but are actually different at the DNS level. This type of attack falls under the category of homograph attacks, where visual similarity is used to deceive users.
The operational impact of CVE-2020-6491 extends beyond simple user deception to potentially enable sophisticated phishing attacks and credential theft operations. Attackers can exploit this vulnerability to make malicious websites appear trustworthy, leading users to unknowingly enter sensitive information or download malicious content. The security implications are particularly severe because users rely heavily on browser security UI elements such as padlock icons, security warnings, and site identity indicators. When these visual cues can be spoofed, the entire security model of the browser becomes compromised, undermining user confidence in the protection mechanisms. This vulnerability directly relates to CWE-170, which addresses improper handling of potentially dangerous input data, and aligns with ATT&CK technique T1566.001, which covers spearphishing through social engineering.
Mitigation strategies for CVE-2020-6491 primarily focus on updating Chrome to version 83.0.4103.61 or later, where Google implemented proper domain name validation and sanitization. Organizations should enforce automatic browser updates and maintain comprehensive patch management procedures to ensure all systems remain protected. Security teams should monitor for indicators of compromise related to suspicious domain names and implement additional network-level protections such as DNS filtering and web content filtering. The vulnerability highlights the importance of robust input validation in security-critical applications and demonstrates why proper handling of internationalized domain names is essential for maintaining browser security. Users should also be educated about the importance of verifying website addresses and not relying solely on visual security indicators, as this vulnerability shows how easily such indicators can be manipulated.