Google Chromium Race Condition Vulnerability
Google Chromium contains a race condition vulnerability that allows a remote attacker to potentially exploit heap corruption via a crafted HTML page. This vulnerability could affect multiple web browsers that utilize Chromium, including, but not limited to, Google Chrome, Microsoft Edge, and Opera.
- Vendor
- Product
- Chromium
- CVSS
- 8.8
- EPSS (exploit probability)
- 24.0%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2021-21166 being exploited?
Yes. CISA added CVE-2021-21166 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 24.0% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-10-19. Full cross-catalog view: /kev-comparison
What to do
CISA required actionApply updates per vendor instructions.
US federal civilian agencies must remediate by (14 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Google Chromium CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2026-2441 Google Chromium CSS Use-After-Free Vulnerability | [ HIGH ] | 8.8 | 55.0% | |
| CVE-2025-14174 Google Chromium Out of Bounds Memory Access Vulnerability | [ HIGH ] | 8.8 | 22.3% | |
| CVE-2025-6558 Google Chromium ANGLE and GPU Improper Input Validation Vulnerability | [ HIGH ] | 8.8 | 10.9% | |
| CVE-2024-4671 Google Chromium Visuals Use-After-Free Vulnerability | [ CRITICAL ] | 9.6 | 8.3% | |
| CVE-2021-37976 Google Chromium Information Disclosure Vulnerability | [ MEDIUM ] | 6.5 | 19.9% |