CVE-2021-21148 in Chrome
Summary
by MITRE • 02/09/2021
Heap buffer overflow in V8 in Google Chrome prior to 88.0.4324.150 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 05/04/2025
The vulnerability CVE-2021-21148 represents a critical heap buffer overflow flaw within the V8 JavaScript engine that powers Google Chrome. This vulnerability exists in versions prior to 88.0.4324.150 and demonstrates a classic memory safety issue that can lead to arbitrary code execution. The flaw occurs when processing crafted HTML content that triggers improper memory management during JavaScript object allocation and manipulation. The vulnerability is categorized under CWE-121 as a heap-based buffer overflow, which arises when more data is written to a buffer located on the heap than the buffer can accommodate, leading to memory corruption.
The technical implementation of this vulnerability involves the V8 engine's handling of JavaScript objects and their underlying memory structures. When Chrome encounters maliciously crafted HTML content containing specific JavaScript constructs, the engine's memory management routines fail to properly validate buffer boundaries during object creation or manipulation. This allows an attacker to write beyond allocated memory regions, potentially overwriting adjacent heap memory locations. The flaw can be exploited through a remote web page that loads malicious JavaScript code, making it particularly dangerous as it requires no user interaction beyond visiting the compromised website. The vulnerability's exploitation pathway aligns with ATT&CK technique T1059.007 for JavaScript execution and T1059.001 for command and scripting interpreter usage.
The operational impact of CVE-2021-21148 extends beyond simple memory corruption, as it provides attackers with a potential pathway for complete system compromise. Successful exploitation can result in arbitrary code execution with the privileges of the Chrome process, potentially allowing attackers to bypass security restrictions and access sensitive system resources. The vulnerability affects all supported platforms where Chrome versions are vulnerable, making it a widespread concern for enterprise environments and individual users. The heap corruption can manifest in various ways including application crashes, data corruption, or more sinisterly, enabling attackers to inject and execute malicious code. This vulnerability represents a significant risk to web-based security as it leverages the fundamental trust users place in web browsers to execute arbitrary code from untrusted sources without proper memory boundary checking.
Organizations and users should prioritize immediate remediation through Chrome version updates to 88.0.4324.150 or later, as this represents the most effective mitigation strategy. Additionally, implementing browser hardening measures such as enabling sandboxing features, restricting JavaScript execution in sensitive contexts, and deploying web application firewalls can provide additional defense layers. Security teams should monitor for exploitation attempts through network traffic analysis and browser security event logging, as the vulnerability's exploitation typically involves specific JavaScript patterns that can be detected through behavioral analysis. The remediation process should include comprehensive testing of updated browser versions to ensure compatibility with existing web applications while maintaining security posture. Regular vulnerability scanning and patch management programs should be enhanced to include automated detection of vulnerable Chrome versions to prevent exploitation attempts.