CVE-2020-6470 in Chrome
Summary
by MITRE
Insufficient validation of untrusted input in clipboard in Google Chrome prior to 83.0.4103.61 allowed a local attacker to inject arbitrary scripts or HTML (UXSS) via crafted clipboard contents.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability identified as CVE-2020-6470 represents a critical cross-site scripting flaw in Google Chrome's handling of clipboard data, specifically affecting versions prior to 83.0.4103.61. This issue falls under the category of insufficient input validation, where the browser fails to properly sanitize or validate clipboard contents that originate from untrusted sources. The vulnerability is particularly concerning because it allows local attackers to exploit the clipboard functionality to inject malicious scripts or HTML code, creating a unique attack vector that leverages the browser's legitimate clipboard handling mechanisms.
The technical exploitation of this vulnerability occurs through the manipulation of clipboard data that Chrome processes without adequate sanitization. When users interact with clipboard operations, the browser's clipboard handling code does not sufficiently validate or escape the content before rendering it in the browser context. This allows an attacker who has access to the victim's system to craft malicious clipboard contents containing HTML or JavaScript that gets executed when the victim pastes or interacts with the clipboard data. The vulnerability specifically targets the user interface elements that process clipboard contents, making it particularly dangerous as it can bypass traditional security measures that protect against external script injection.
The operational impact of CVE-2020-6470 extends beyond simple script execution, as it enables a form of persistent cross-site scripting that can be particularly effective in targeted attacks. Attackers can leverage this vulnerability to execute malicious code in the context of the victim's browsing session, potentially leading to session hijacking, data exfiltration, or further exploitation of the victim's browser environment. The local attacker requirement means that the threat actor must already have some level of access to the victim's system, but this access can be gained through various means such as phishing, malware, or physical access. The vulnerability's classification aligns with CWE-79, which describes Cross-Site Scripting, and can be mapped to ATT&CK technique T1059.007 for JavaScript execution, demonstrating how clipboard manipulation can serve as an attack surface for code injection.
The remediation for this vulnerability required Google to implement proper input validation and sanitization of clipboard contents within Chrome's rendering pipeline. The fix involved ensuring that any data processed from the clipboard undergoes appropriate escaping and validation before being rendered in the browser context. This update aligns with security best practices for preventing XSS vulnerabilities and represents a critical defensive measure that should be implemented across all affected browser versions. Organizations should prioritize updating Chrome installations to version 83.0.4103.61 or later to mitigate this risk, as the vulnerability could enable attackers to establish persistent footholds within victim environments through seemingly benign clipboard interactions. The vulnerability serves as a reminder of the importance of validating all user input, including data from system-level interactions like clipboard operations, and demonstrates how traditional security boundaries can be bypassed through creative exploitation of legitimate browser features.