CVE-2021-21166VulnerabilityPublished 11/03/2021Updated 10/24/2026

CVE-2021-21166: Google Chromium Race Condition Vulnerability

Affects Google ChromiumSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 11/03/2021
KEV deadline: 11/17/2021
EPSS: 24.0% chance of exploitation in 30 days – higher than 97% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2021-21166 (opens in a new tab)

Description

CVE-2021-21166 is a race condition vulnerability in Google Chromium that can be exploited remotely via a crafted HTML page to cause heap corruption. This flaw affects multiple Chromium-based browsers including Google Chrome, Microsoft Edge, and Opera. The vulnerability has been exploited in the wild. No specific affected versions or patch information is provided in the input data.

Summary

Google Chromium contains a race condition vulnerability (CWE-362) that allows remote attackers to potentially trigger heap corruption (CWE-122) by serving a specially crafted HTML page. This vulnerability impacts multiple browsers built on Chromium, such as Google Chrome, Microsoft Edge, and Opera. Exploitation has been observed in the wild, indicating active threat usage. No patch or remediation details are included in the provided information.

Impact

Successful exploitation can lead to heap corruption, which may result in arbitrary code execution or browser compromise. The vulnerability is remotely exploitable via web content, affecting end users of Chromium-based browsers. Active exploitation in the wild increases the risk to users.

Mitigation

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Users and administrators should monitor official Google Chromium security advisories for updates and apply patches promptly once available.

CVE-2021-21166: Google Chromium Race Condition Vulnerability

What to do

Description

Summary

Impact

Mitigation

Weaknesses

References

What to do

Description

AnalysisAI-generated, updated 10/24/2026, 09:26:23 UTC

Weaknesses

References

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