---
id: "CVE-2021-21148"
kind: "vulnerability"
aliases: ["CVE-2021-21148"]
title: "Google Chromium V8: Google Chromium V8 Heap Buffer Overflow Vulnerability"
severity: "high"
cvss: 8.8
epss: 0.19968
exploited: true
status: "open"
category: "runtime"
products: [{"name": "Google Chromium V8", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["browsers", "chrome", "chromium", "edge", "exploited", "opera", "runtime"]
not_affected_if: ["non-chromium-browsers"]
published_at: "2021-02-09T16:15:12+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-2021-21148", "first_seen_at": "2026-10-23T19:11:53+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2021-21148", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21148", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Google Chromium V8: Google Chromium V8 Heap Buffer Overflow Vulnerability

A heap buffer overflow in the Chromium V8 JavaScript engine lets a remote attacker corrupt heap memory by serving a crafted HTML page. Exploitation in the wild is listed in CISA's KEV catalog, which means an attacker can likely run code in the browser's renderer.

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

## Affected

- vendor:Google Chromium V8 affected ? fixed ?

## How to check

Check the installed browser version (chrome://version in Chrome, edge://version in Edge) and compare it to the fixed release the vendor published.

## Fix

Update Google Chrome, Microsoft Edge, Opera and other Chromium-based browsers to the latest stable release.
Update per vendor instructions as CISA requires; the fixed version numbers are not in the sources.

## Timeline

- 2026-10-23T19:11:53+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-21148
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2021-21148
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-21148

## From the sources

Google Chromium V8 Engine contains a heap buffer overflow 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_