{"id":"CVE-2021-4102","kind":"vulnerability","aliases":["CVE-2021-4102"],"related":[],"title":"Google Chromium V8: Google Chromium V8 Use-After-Free Vulnerability","description":"Google Chromium V8 Engine 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.\n\nCISA required action: Apply updates per vendor instructions.","summary":"A use-after-free bug in the V8 JavaScript engine used by Chromium lets a remote attacker corrupt heap memory with a crafted HTML page. Attackers can use this to run code inside the browser, and it is confirmed exploited in the wild.","severity":"high","cvss":8.8,"epss":0.07836,"exploited":true,"exploited_at":"2021-12-15T00:00:00+00:00","products":[{"name":"Google Chromium V8","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["browsers","chrome","chromium","edge","exploited","opera","runtime"],"not_affected_if":["unpatched-builds-not-in-use"],"how_to_check":"Open chrome://version (or edge://version, opera://about) and compare the version to the fixed release listed by the vendor.","fix":"Update Chrome, Edge, Opera or other Chromium-based browsers to the vendor's patched release; unknown for the exact fixed version in these sources.\nApply vendor updates per CISA guidance.","status":"open","published_at":"2021-12-15T00:00:00+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:31:49+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-10-23T21:31:49Z","model":"claude-haiku-5-5","output":{"fix":"Update Chrome, Edge, Opera or other Chromium-based browsers to the vendor's patched release; unknown for the exact fixed version in these sources.\nApply vendor updates per CISA guidance.","reach":"internet","impact":"high","summary":"A use-after-free bug in the V8 JavaScript engine used by Chromium lets a remote attacker corrupt heap memory with a crafted HTML page. Attackers can use this to run code inside the browser, and it is confirmed exploited in the wild.","category":"runtime","who_cares":["chromium","chrome","edge","opera","browsers"],"confidence":0.6,"needs_auth":"no","worst_case":"Attacker runs code in the browser after the victim visits a crafted page.","analyst_note":"Find the exact fixed Chromium version and the Chrome stable release notes for CVE-2021-4102 to write a concrete how_to_check and fix.","how_to_check":"Open chrome://version (or edge://version, opera://about) and compare the version to the fixed release listed by the vendor.\nunknown\nunknown","needs_analyst":true,"not_affected_if":["unpatched-builds-not-in-use"],"user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"high"},"cost_usd":0.000509,"input_tokens":2889,"output_tokens":440,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':13A,16A '-4102':14A,17A 'action':121C 'affect':101C 'allow':84C 'appli':122C 'attack':45B,54B,87C 'browser':21B,63B,104C 'bug':33B 'chrome':22B,114C 'chromium':2A,5A,19A,23B,41B,73C,107C 'cisa':119C 'code':60B 'confirm':67B 'contain':76C 'corrupt':46B,92C 'could':100C 'craft':51B,95C 'cve':12A,15A 'edg':24B,116C 'engin':38B,75C 'exploit':25B,68B,90C 'free':10A,32B,81C 'googl':1A,4A,72C,113C 'google':18A 'heap':47B,91C 'html':52B,96C 'includ':108C 'insid':61B 'instruct':126C 'javascript':37B 'let':42B 'limit':111C 'memori':48B 'microsoft':115C 'multipl':102C 'opera':26B,118C 'page':53B,97C 'per':124C 'potenti':89C 'remot':44B,86C 'requir':120C 'run':59B 'runtim':27B 'updat':123C 'use':8A,30B,39B,56B,79C 'use-after-fre':7A,29B,78C 'util':106C 'v8':3A,6A,20A,36B,74C 'vendor':125C 'via':93C 'vulner':11A,82C,99C 'web':103C 'wild':71B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-12-15T00:00:00+00:00","kev":{"dateAdded":"2021-12-15","dueDate":"2021-12-29","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-2021-4102","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-4102","severity":null,"published_at":"2021-12-15T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T16:39:49+00:00","note":null},{"source":"epss","external_id":"CVE-2021-4102","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-4102","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-2021-4102","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-4102","severity":null,"published_at":"2022-02-11T23:15:08+00:00","modified_at":"2026-06-17T04:19:02+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"}