Google Chrome Audio Component Data Race Remote Code Execution Vulnerability (CVE-2021-21166)
Executive & SecOps Summary
SECOPS ASSESSMENTGoogle Chrome prior to version 89.0.4389.72
Remote attackers can trigger heap corruption via a crafted HTML page, potentially leading to arbitrary code execution within the browser process
Immediately update Google Chrome to the latest stable version (89.0.4389.72 or higher)
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
To mitigate this vulnerability, upgrade Google Chrome to version 89.0.4389.72 or later. For Linux environments, use the following package manager commands:
# For Debian/Ubuntu-based systems
sudo apt-get update && sudo apt-get --only-upgrade install google-chrome-stable -y
# For RedHat/CentOS/Fedora-based systems
sudo dnf upgrade google-chrome-stable -y2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, enforce Chrome auto-updates via Group Policy Objects (GPO) or registry keys, and restrict access to untrusted external websites using secure web gateways.
# Force Google Chrome Auto-Update via Windows Registry
New-Item -Path 'HKLM:\SOFTWARE\Policies\Google\Update' -Force
Set-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Google\Update' -Name 'UpdateDefault' -Value 1
Set-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Google\Update' -Name 'AutoUpdateCheckPeriodMinutes' -Value 14403. Log Audit & IoC Verification Commands
Use the following script to audit the installed Google Chrome version on endpoints to identify vulnerable installations.
# Bash script to verify Google Chrome version on Linux endpoints
chrome_version=$(google-chrome --version | awk '{print $3}')
required_version='89.0.4389.72'
if [ '$(printf '%s\
' '$required_version' '$chrome_version' | sort -V | head -n1)' = '$required_version' ]; then
echo '[SAFE] Chrome version is up-to-date: '$chrome_version
else
echo '[WARNING] Vulnerable Chrome version detected: '$chrome_version'. Upgrade immediately.'
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Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-21166) is a data race condition (CWE-362) existing within the audio processing component of Google Chrome. Due to inadequate synchronization mechanisms when handling shared audio resources across multiple threads, concurrent read/write or write/free operations can occur. This race condition leads to memory pointer corruption, resulting in a heap corruption state.
2. Exploitation Mechanics & Attack Scenario
An attacker can exploit this vulnerability by hosting a specially crafted HTML page containing malicious scripts that manipulate audio streams (e.g., via Web Audio APIs). When a victim visits the malicious page, the script triggers a race condition between the audio processing threads in the renderer process. By precisely timing the memory operations, the attacker can corrupt heap memory structures, potentially leading to a Use-After-Free scenario and executing arbitrary code within the context of the browser renderer.
3. Infrastructure & Business Impact
As this vulnerability is listed in the CISA KEV (Known Exploited Vulnerabilities) catalog, active exploitation in the wild has been confirmed. If combined with a sandbox escape vulnerability, an attacker could gain full system privileges on the victim's machine, leading to unauthorized access to corporate networks, data exfiltration, and potential malware deployment across the enterprise infrastructure.
Official Vendor Advisories & References
Data race in audio in Google Chrome prior to 89.0.4389.72 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
Frequently Asked SecOps Questions (CVE-2021-21166)
FAQQ1. How critical is CVE-2021-21166 and is it actively exploited in the wild?
CVE-2021-21166 is rated CVSS 8.8 (HIGH) with a 30-day EPSS exploitation probability of 24.0%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-21166?
Primary impacted vendors include google across chrome. Scope summary: Google Chrome prior to 89.0.4389.72 (All desktop platforms including Windows, macOS, and Linux)
Q3. What temporary mitigations or workarounds exist for CVE-2021-21166 before patching?
[Mitigation] Immediately update Google Chrome to the latest stable version (89.0.4389.72 or higher) Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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