CVE-2021-21220

Google Chromium V8 Improper Input Validation Vulnerability

High 8.8
Exploited: added to CISA KEV 3 Nov 2021

Description

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.

Key facts

Published: 26 Apr 2021
Last changed: 21 Oct 2025
Assigned by: Chrome
KEV added: 3 Nov 2021
KEV fix due: 17 Nov 2021
EPSS: 70.435% likely to be exploited in the next 30 days, higher than 99.399% of CVEs (scores for 15 Nov 2026)
SSVC (CISA): Exploitation: active; Automatable: no; Technical impact: total

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

8.8CVSS 3.1, Highfrom CISA (ADP container)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

What to do

Apply updates per vendor instructions.CISA KEV required action

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

Vendor	Product	Versions
Google	Chrome	unspecified up to but excluding 89.0.4389.128 (affected)