CVE-2020-6513: 
Google Chrome vulnerability analysis and mitigation

A heap buffer overflow vulnerability (CVE-2020-6513) was discovered in PDFium, a component of Google Chrome, prior to version 84.0.4147.89. The vulnerability was discovered on June 4, 2020, and was patched by Google on June 6, 2020. This security flaw affects the PDF rendering functionality in Google Chrome and could be exploited through specially crafted PDF files (Talos Intelligence, NVD).

The vulnerability exists in the way Google Chrome 83.0.4103.61 executes JavaScript inside PDF documents. The issue stems from the difference in how 'this' object is handled in PDF document JavaScript compared to regular JavaScript execution environments. The vulnerability involves a circular proto chain assignment that should normally result in an error but succeeds in this context, leading to memory corruption. The vulnerability has been assigned a CVSS v3.1 base score of 8.8 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (Talos Intelligence, NVD).

The vulnerability could allow an attacker to cause out-of-bounds memory access through a specially crafted PDF document or webpage. This could potentially lead to arbitrary code execution, though user interaction is required as the victim must open a malicious PDF document or visit a malicious webpage (Talos Intelligence).

To exploit this vulnerability, an attacker would need to create a specially crafted PDF file or webpage that contains malicious JavaScript code. The vulnerability requires user interaction, as the victim must open the malicious PDF document or visit the malicious webpage. The proof of concept demonstrates that the vulnerability can be triggered through specific JavaScript code manipulation within PDF documents (Talos Intelligence).

The vulnerability was patched in Google Chrome version 84.0.4147.89. Users and administrators should ensure their Chrome installations are updated to this version or later. Various Linux distributions have also released security updates to address this vulnerability, including Debian, Fedora, and Gentoo (Chrome Release, Debian Security).