---
id: "CVE-2021-21206"
kind: "vulnerability"
aliases: ["CVE-2021-21206"]
title: "Google Chromium Blink: Google Chromium Blink Use-After-Free Vulnerability"
severity: "high"
cvss: 8.8
epss: 0.09307
exploited: true
status: "open"
category: "runtime"
products: [{"name": "Google Chromium Blink", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["chrome", "chromium", "edge", "electron", "end-users", "exploited", "opera", "runtime"]
not_affected_if: ["already-updated-browser"]
published_at: "2021-04-26T17:15:08+00:00"
first_seen_at: "2026-10-23T19:11:53+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-21206", "first_seen_at": "2026-10-23T19:11:53+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2021-21206", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21206", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Google Chromium Blink: Google Chromium Blink Use-After-Free Vulnerability

A use-after-free bug in Chromium's Blink rendering engine lets a remote attacker corrupt heap memory by serving a crafted HTML page. Attackers can use this to run code inside the browser when a user visits the page, and CISA lists it as actively exploited.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Google Chromium Blink affected ? fixed ?

## How to check

Open chrome://version (or edge://version, opera://version) and compare the Chromium version with the fixed release in the vendor advisory.

## Fix

Update Chrome, Edge, Opera or other Chromium-based browsers to the fixed release named in the vendor advisory.
CISA required action: apply updates per vendor instructions.

## Timeline

- 2026-10-23T19:11:53+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-21206
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2021-21206
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-21206

## From the sources

Google Chromium Blink contains a use-after-free 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.

CISA required action: Apply updates per vendor instructions.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_