How severe is CVE-2021-21166?

CVE-2021-21166 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21166 being actively exploited?

Yes. CVE-2021-21166 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2021-21166?

CVE-2021-21166 primarily affects Google Chrome. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-21166?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2021-21166 have an EU (EUVD) identifier?

Yes. CVE-2021-21166 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-8557. It is also flagged as exploited in the EUVD (since 2021-11-03).

When was CVE-2021-21166 published?

CVE-2021-21166 was published on 2021-03-09 and last updated on 2026-06-17.

CVE-2021-21166

CVE-2021-21166 is a high-severity vulnerability in Google Chrome with a CVSS 3.x base score of 8.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2021-11-03). The underlying weakness is classified as CWE-362.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 27% (98th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2021-11-03)
EU (EUVD) id: EUVD-2021-8557
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2021-11-03)
Weakness: CWE-362
Affected product: Google Chrome
Published: 2021-03-09
Last modified: 2026-06-17

Description

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 questions

What is CVE-2021-21166?: 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.
How severe is CVE-2021-21166?: CVE-2021-21166 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21166 being actively exploited?: Yes. CVE-2021-21166 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2021-21166?: CVE-2021-21166 primarily affects Google Chrome. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-21166?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2021-21166 have an EU (EUVD) identifier?: Yes. CVE-2021-21166 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-8557. It is also flagged as exploited in the EUVD (since 2021-11-03).
When was CVE-2021-21166 published?: CVE-2021-21166 was published on 2021-03-09 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

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