CVE-2021-21149: Google Chrome Buffer Overflow Vulnerability

CVE-2021-21149 Overview

CVE-2021-21149 is a stack buffer overflow vulnerability in the Data Transfer component of Google Chrome on Linux. This vulnerability allows a remote attacker to perform out-of-bounds memory access via a crafted HTML page. The flaw exists in versions of Google Chrome prior to 88.0.4324.182, and successful exploitation could lead to arbitrary code execution, information disclosure, or denial of service conditions.

Critical Impact

Remote attackers can exploit this vulnerability through malicious web pages to gain out-of-bounds memory access, potentially leading to code execution with the privileges of the browser process.

Affected Products

• Google Chrome (versions prior to 88.0.4324.182)
• Linux Kernel (as the underlying operating system)
• Fedora 32 and Fedora 33 (distributions shipping vulnerable Chrome versions)

Discovery Timeline

• 2021-02-22 - CVE-2021-21149 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-21149

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), which occurs when the software writes data past the end, or before the beginning, of the intended buffer. In the context of the Data Transfer component in Google Chrome, improper boundary checks allow an attacker to craft a malicious HTML page that triggers a stack buffer overflow condition.

The vulnerability requires user interaction—specifically, a victim must navigate to a malicious webpage. Once exploited, the attacker can perform out-of-bounds memory operations, which may corrupt adjacent memory structures on the stack. This can potentially be leveraged to hijack control flow, execute arbitrary code, or crash the browser process.

Root Cause

The root cause of CVE-2021-21149 lies in insufficient bounds checking within the Data Transfer component when processing specific HTML content. Stack-based buffers have fixed sizes, and when input data exceeds these boundaries without proper validation, the overflow corrupts adjacent stack memory. This implementation flaw in Chrome's Linux-specific Data Transfer handling creates an exploitable condition through carefully crafted web content.

Attack Vector

The attack vector for this vulnerability is network-based, requiring a victim to visit a malicious website or be redirected to one. The attacker must craft a specific HTML page designed to trigger the buffer overflow in the Data Transfer component. No privileges are required on the target system, but user interaction is necessary to navigate to the malicious content. Upon successful exploitation, the attacker gains the ability to perform out-of-bounds memory access operations, which can be chained with other techniques to achieve code execution.

The vulnerability specifically affects Google Chrome on Linux systems, indicating platform-specific behavior in the Data Transfer implementation that differs from other operating systems.

Detection Methods for CVE-2021-21149

Indicators of Compromise

• Unexpected browser crashes or instability when loading specific web pages
• Anomalous memory access patterns in Chrome processes on Linux systems
• Presence of suspicious HTML files or cached web content designed to exploit Data Transfer functionality
• Chrome process termination logs indicating memory corruption or segmentation faults

Detection Strategies

• Monitor Chrome browser version across endpoints to identify installations running versions prior to 88.0.4324.182
• Implement endpoint detection rules for anomalous Chrome process behavior, particularly stack-based memory violations
• Deploy web filtering to block access to known malicious domains serving exploit payloads
• Review Chrome crash reports for patterns consistent with buffer overflow exploitation

Monitoring Recommendations

• Enable enhanced logging for browser crashes and memory-related errors on Linux workstations
• Monitor network traffic for suspicious HTML content delivery patterns targeting Chrome users
• Track Chrome update deployment status across the organization to ensure timely patching
• Configure SentinelOne to alert on behavioral indicators associated with browser exploitation attempts

How to Mitigate CVE-2021-21149

Immediate Actions Required

• Update Google Chrome to version 88.0.4324.182 or later immediately
• Verify all Linux systems running Chrome have automatic updates enabled
• Audit Chrome installations across the organization to identify vulnerable versions
• Consider restricting browser access to untrusted websites until patching is complete

Patch Information

Google has released a security update addressing this vulnerability. The fix is included in Chrome version 88.0.4324.182 and all subsequent releases. Organizations should update Chrome through their standard software management processes. For detailed information about the security update, refer to the Google Chrome Desktop Update. Additional technical details can be found in the Chrome Bug Report #1138143.

Fedora users should apply updates from the distribution's package repositories, as security updates have been distributed via the Fedora Package Announcement. Gentoo users can reference the Gentoo GLSA 2021-04-08 for guidance.

Workarounds

• Limit browsing to trusted websites only until patches can be applied
• Consider using alternative browsers temporarily on Linux systems if Chrome cannot be immediately updated
• Implement network-based web filtering to block potentially malicious content
• Enable Chrome's Site Isolation feature to provide additional defense-in-depth

# Verify Chrome version on Linux
google-chrome --version

# Update Chrome on Debian/Ubuntu-based systems
sudo apt update && sudo apt install --only-upgrade google-chrome-stable

# Update Chrome on Fedora
sudo dnf update chromium