# CVE-2021-21220: Google Chromium V8 Improper Input Validation Vulnerability

- Exploited (CISA KEV): yes, added 2021-11-03
- Published: 2021-04-26
- CVSS: 8.8 HIGH (v3.1)
- EPSS: 70.4% (99th percentile)
- CWE: CWE-20, CWE-122

Insufficient validation of untrusted input in V8 in Google Chrome prior to 89.0.4389.128 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Before feed history | — | — |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | Before feed history | — | — |
| Fastly | Before feed history | — | — |
| F5 | Before feed history | — | — |
| Akamai | No public source | — | — |
| OWASP CRS | Before feed history | — | — |

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2021-21220 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2021-21220