{"id":"CVE-2021-21220","kind":"vulnerability","aliases":["CVE-2021-21220"],"related":[],"title":"Google Chromium V8: Google Chromium V8 Improper Input Validation Vulnerability","description":"Google Chromium V8 Engine contains an improper input validation 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.\n\nCISA required action: Apply updates per vendor instructions.","summary":"A flaw in the V8 JavaScript engine used by Chromium browsers lets a remote attacker corrupt heap memory with a crafted HTML page. Successful exploitation can lead to arbitrary code execution in the browser.","severity":"high","cvss":8.8,"epss":0.70435,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Google Chromium V8","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["browsers","chrome","chromium","edge","exploited","opera","runtime"],"not_affected_if":["fixed-browser-version"],"how_to_check":"Open chrome://version (or edge://version, opera://about) and compare the version with the fixed release in the vendor advisory.","fix":"Update Google Chrome, Microsoft Edge, Opera and other Chromium-based browsers to a release that includes the vendor's V8 fix.","status":"open","published_at":"2021-04-26T17:15:08+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:39:22+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-10-23T21:39:22Z","model":"claude-haiku-5-5","output":{"fix":"Update Google Chrome, Microsoft Edge, Opera and other Chromium-based browsers to a release that includes the vendor's V8 fix.\nunknown","reach":"internet","impact":"high","summary":"A flaw in the V8 JavaScript engine used by Chromium browsers lets a remote attacker corrupt heap memory with a crafted HTML page. Successful exploitation can lead to arbitrary code execution in the browser.","category":"runtime","who_cares":["chromium","chrome","edge","opera","browsers"],"confidence":0.6,"needs_auth":"no","worst_case":"Attacker runs arbitrary code in the victim's browser via a crafted web page.","analyst_note":"Sources do not list fixed versions or affected ranges; check the Chrome Releases blog and the Chromium V8 bug entry for CVE-2021-21220.","how_to_check":"Open chrome://version (or edge://version, opera://about) and compare the version with the fixed release in the vendor advisory.\nunknown\nunknown","needs_analyst":true,"not_affected_if":["fixed-browser-version"],"user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"high"},"cost_usd":0.0005,"input_tokens":2890,"output_tokens":421,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':12A,15A '-21220':13A,16A 'action':109C 'affect':89C 'allow':72C 'appli':110C 'arbitrari':55B 'attack':41B,75C 'browser':20B,37B,60B,92C 'chrome':21B,102C 'chromium':2A,5A,18A,22B,36B,62C,95C 'cisa':107C 'code':56B 'contain':65C 'corrupt':42B,80C 'could':88C 'craft':47B,83C 'cve':11A,14A 'edg':23B,104C 'engin':33B,64C 'execut':57B 'exploit':24B,51B,78C 'flaw':28B 'googl':1A,4A,61C,101C 'google':17A 'heap':43B,79C 'html':48B,84C 'improp':7A,67C 'includ':96C 'input':8A,68C 'instruct':114C 'javascript':32B 'lead':53B 'let':38B 'limit':99C 'memori':44B 'microsoft':103C 'multipl':90C 'opera':25B,106C 'page':49B,85C 'per':112C 'potenti':77C 'remot':40B,74C 'requir':108C 'runtim':26B 'success':50B 'updat':111C 'use':34B 'util':94C 'v8':3A,6A,19A,31B,63C 'valid':9A,69C 'vendor':113C 'via':81C 'vulner':10A,70C,87C 'web':91C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-04-26T17:15:08+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-21220","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-21220","severity":null,"published_at":"2021-11-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T20:35:38+00:00","note":null},{"source":"epss","external_id":"CVE-2021-21220","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-21220","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:44+00:00","fetched_at":"2026-10-23T19:13:44+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-21220","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21220","severity":null,"published_at":"2021-04-26T17:15:08+00:00","modified_at":"2026-06-17T03:35:03+00:00","first_seen_at":"2026-10-23T21:57:35+00:00","fetched_at":"2026-10-23T21:57:35+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}