{"id":"CVE-2021-21148","kind":"vulnerability","aliases":["CVE-2021-21148"],"related":[],"title":"Google Chromium V8: Google Chromium V8 Heap Buffer Overflow Vulnerability","description":"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.\n\nCISA required action: Apply updates per vendor instructions.","summary":"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.","severity":"high","cvss":8.8,"epss":0.19968,"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":["non-chromium-browsers"],"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.\nUpdate per vendor instructions as CISA requires; the fixed version numbers are not in the sources.","status":"open","published_at":"2021-02-09T16:15:12+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:39:33+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-23T21:39:33Z","model":"claude-haiku-5-5","output":{"fix":"Update Google Chrome, Microsoft Edge, Opera and other Chromium-based browsers to the latest stable release.\nUpdate per vendor instructions as CISA requires; the fixed version numbers are not in the sources.","reach":"internet","impact":"high","summary":"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.","category":"runtime","who_cares":["chrome","edge","opera","chromium","browsers"],"confidence":0.7,"needs_auth":"no","worst_case":"Attacker runs code in the browser renderer via a malicious web page.","analyst_note":"Find the fixed Chrome/Edge version and the NVD/Chromium release notes for CVE-2021-21148 to fill in how_to_check and fix.","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.\nunknown\nunknown","needs_analyst":true,"not_affected_if":["non-chromium-browsers"],"user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"high"},"cost_usd":0.000522,"input_tokens":2896,"output_tokens":465,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':12A,15A '-21148':13A,16A 'action':122C 'affect':102C 'allow':85C 'appli':123C 'attack':40B,64B,88C 'browser':20B,71B,105C 'buffer':8A,29B,81C 'catalog':60B 'chrome':21B,115C 'chromium':2A,5A,18A,22B,33B,75C,108C 'cisa':57B,120C 'code':68B 'contain':78C 'corrupt':41B,93C 'could':101C 'craft':47B,96C 'cve':11A,14A 'edg':23B,117C 'engin':36B,77C 'exploit':24B,50B,91C 'googl':1A,4A,74C,114C 'google':17A 'heap':7A,28B,42B,80C,92C 'html':48B,97C 'includ':109C 'instruct':127C 'javascript':35B 'kev':59B 'let':37B 'like':66B 'limit':112C 'list':55B 'mean':62B 'memori':43B 'microsoft':116C 'multipl':103C 'opera':25B,119C 'overflow':9A,30B,82C 'page':49B,98C 'per':125C 'potenti':90C 'remot':39B,87C 'render':73B 'requir':121C 'run':67B 'runtim':26B 'serv':45B 'updat':124C 'util':107C 'v8':3A,6A,19A,34B,76C 'vendor':126C 'via':94C 'vulner':10A,83C,100C 'web':104C 'wild':53B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-02-09T16:15:12+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-2021-21148","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-21148","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":"2026-10-25T10:39:08+00:00","note":null},{"source":"epss","external_id":"CVE-2021-21148","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-21148","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-2021-21148","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21148","severity":null,"published_at":"2021-02-09T16:15:12+00:00","modified_at":"2026-06-17T03:34:54+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"}