Exploited CVEs / Google / CVE-2021-30563

CVE-2021-30563

Google Chromium V8 Type Confusion Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2021-11-17 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Chrome Releases (security updates), linked below.

Risk summary

HighCISA KEV

8.8

CVSS base

8.9%

EPSS exploit probability

High

Severity

2021-11-03

Added to KEV

2021-11-17 (past due)

CISA due date

Actively exploited Google Chromium V8 vulnerability, High severity, CVSS 8.8. Added to the CISA KEV catalog 2021-11-03.

Senserva AI read on CVE-2021-30563 CISA required action Official fix for CVE-2021-30563 Admin questions

Senserva AI Opinion for CVE-2021-30563

This is a V8 type confusion flaw that lets a crafted HTML page trigger heap corruption, meaning a user only needs to visit a malicious site to be at risk. Because V8 is shared, exposure extends beyond Google Chrome to any Chromium based browser such as Edge, Brave, and Opera. CISA confirmed active exploitation and added it to the KEV catalog on 2021-11-03, so this is not theoretical.

Do this: Push the patched Chrome and Chromium browser versions to all endpoints now and confirm your Edge, Brave, and other Chromium based browsers are also updated.

AI-generated from public data, 2026-07-22. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2021-30563

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I run IT security. Facts for CVE-2021-30563, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2021-30563.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2021-30563: Google Chromium V8 Type Confusion Vulnerability
- Affected: Google Chromium V8
- Severity: High, CVSS 8.8; EPSS 30-day exploitation probability 8.9%
- Added to CISA KEV: 2021-11-03; federal remediation due 2021-11-17
- Ransomware-linked: no
- CISA required action: Apply updates per vendor instructions.
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) The fastest safe path to remediation. 4) How to check whether my environment is exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Patch now

Exploited in the wild: confirmed by the CISA KEV catalog, not predicted.

The fix ships from the vendor: Chrome Releases (security updates).

Do this now: Federal remediation deadline 2021-11-17; treat it as your outer bound. Patch now and verify deployment on every exposed device.

Updated August 14, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2021-30563

Published: 2021-11-03
Last revised: 2021-11-03
Changes tracked: 1

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

Senserva Watchevery change we have recorded for this one

What changed, and when

2021-11-03 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 8.8; EPSS first scored at 8.9%

Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.

CISA required action

Federal (BOD 22-01) remediation due date: 2021-11-17 (past due).

Apply updates per vendor instructions.

Official fix for CVE-2021-30563

The authoritative fix and affected-version list are published by the vendor. Find the Chromium V8 advisory on Chrome Releases (security updates).

Chrome Releases (security updates)CISA KEV entry

Common questions about CVE-2021-30563

Is CVE-2021-30563 actively exploited?

Yes. CVE-2021-30563 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 8.9%.

What is the CISA deadline and required action for CVE-2021-30563?

CISA set the federal (BOD 22-01) remediation due date at 2021-11-17, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply updates per vendor instructions.

What fixes CVE-2021-30563?

The authoritative fix is in the vendor advisory: see Chrome Releases (security updates) for the patched Chromium V8 versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.

Can I ask my own AI about CVE-2021-30563?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2021-30563's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).

Scope and sources

More exploited Google CVEs: CVE-2026-11645 CVE-2026-5281 CVE-2026-3910 CVE-2026-3909 CVE-2026-2441 CVE-2025-14174 CVE-2025-13223 CVE-2025-10585
All Google exploited CVEs on one page: Google vulnerabilities actively exploited.
Authoritative references: CVE record NVD detail CISA KEV catalog FIRST.org EPSS

Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.