CVE-2019-5791 in Chrome
Summary
by MITRE
Inappropriate optimization in V8 in Google Chrome prior to 73.0.3683.75 allowed a remote attacker to perform an out of bounds memory read via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/15/2020
The vulnerability identified as CVE-2019-5791 represents a critical optimization flaw within the V8 JavaScript engine that powers Google Chrome and other Chromium-based browsers. This issue stems from an improper handling of memory operations during the JavaScript compilation process, specifically affecting the optimization phase where the engine attempts to improve performance by reorganizing code execution patterns. The vulnerability manifests when the V8 engine optimizes code containing array operations, particularly in scenarios involving sparse arrays or arrays with unusual indexing patterns that do not conform to typical JavaScript array behavior expectations.
The technical flaw occurs at the bytecode optimization level where V8's optimizing compiler makes incorrect assumptions about memory layout and array bounds checking. When processing crafted HTML pages containing malicious JavaScript code, the optimizer incorrectly calculates memory access patterns, leading to situations where the engine attempts to read from memory locations that are outside the bounds of allocated array structures. This misoptimization bypasses normal memory safety checks that would typically prevent such out-of-bounds access, creating a pathway for remote attackers to potentially extract sensitive information from memory or cause arbitrary code execution depending on the specific memory layout and content accessed.
The operational impact of this vulnerability extends beyond simple information disclosure, as it represents a fundamental flaw in the memory safety mechanisms of one of the most widely used web browsers globally. Attackers can exploit this vulnerability by hosting malicious web pages that trigger the specific optimization path, requiring no user interaction beyond visiting the page. The remote nature of the attack means that victims can be compromised simply by loading a malicious webpage, making this vulnerability particularly dangerous in phishing campaigns or compromised websites. The vulnerability affects all versions of Chrome prior to 73.0.3683.75 and impacts users running these vulnerable versions across all supported operating systems, creating a significant attack surface for threat actors targeting web-based exploits.
Security researchers have classified this vulnerability according to CWE-125 as an "Out-of-bounds Read" which directly aligns with the memory access violation patterns observed in the exploit. The attack vector maps to the ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript" as attackers leverage JavaScript code to trigger the vulnerable optimization path. Mitigation strategies should focus on immediate browser updates to version 73.0.3683.75 or later, which contain patches addressing the optimization logic that causes the incorrect memory access patterns. Organizations should also implement network-level protections such as content security policies and web application firewalls to limit exposure, while security teams should monitor for indicators of compromise related to this specific vulnerability through endpoint detection and response systems that can identify attempts to exploit the memory access violation patterns.