{"id":"CVE-2026-121253","kind":"vulnerability","aliases":["CVE-2026-121253"],"related":[],"title":"Chrome: DevTools flaw lets a crafted extension bypass site isolation","description":"Missing authorization in DevTools in Google Chrome prior to 157.0.8103.38 allowed a remote attacker leveraging social engineering to bypass site isolation via a crafted Chrome extension. (Chromium security severity: Low)","summary":"A missing authorization check in Chrome's DevTools lets a remote attacker, using social engineering and a crafted Chrome extension, bypass site isolation. Chromium rates the severity Low.","severity":"low","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["chrome","desktop-browsers","runtime"],"not_affected_if":["chrome-updated","extensions-restricted"],"how_to_check":"- Check the Chrome version: open `chrome://settings/help` and compare against `157.0.8103.38`.\n- Review installed extensions at `chrome://extensions` for anything unexpected.","fix":"- Google Chrome: move to `157.0.8103.38` or later.","status":"open","published_at":"2026-11-03T21:17:36+00:00","first_seen_at":"2026-11-03T21:19:29+00:00","triaged_at":"2026-11-03T21:20:56+00:00","updated_at":"2026-11-03T21:20:56+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-11-03T21:20:56Z","model":"claude-haiku-5-5","output":{"fix":"- Google Chrome: move to `157.0.8103.38` or later.","reach":"internet","title":"Chrome: DevTools flaw lets a crafted extension bypass site isolation","impact":"medium","summary":"A missing authorization check in Chrome's DevTools lets a remote attacker, using social engineering and a crafted Chrome extension, bypass site isolation. Chromium rates the severity Low.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["chrome","desktop-browsers"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"Attacker bypasses site isolation to read data from other sites","analyst_note":"","how_to_check":"- Check the Chrome version: open `chrome://settings/help` and compare against `157.0.8103.38`.\n- Review installed extensions at `chrome://extensions` for anything unexpected.","plain_action":"Update Google Chrome to version 157.0.8103.38 or later, and remove any extensions you do not recognise.","needs_analyst":false,"not_affected_if":["chrome-updated","extensions-restricted"],"who_is_affected":"Anyone running Google Chrome older than 157.0.8103.38. Exploitation needs a person to be tricked into installing a crafted extension, so managed browsers that restrict extension installs are less exposed. unknown for any further configuration detail.","user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"low"},"cost_usd":0.000671,"input_tokens":4105,"output_tokens":520,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-121253':13A,16A '-2026':12A,15A '157.0.8103.38':59C 'allow':60C 'attack':33B,63C 'author':24B,51C 'browser':20B 'bypass':8A,42B,68C 'check':25B 'chrome':1A,17B,27B,40B,56C,74C 'chromium':45B,76C 'craft':6A,39B,73C 'cve':11A,14A 'desktop':19B 'desktop-brows':18B 'devtool':2A,29B,53C 'engin':36B,66C 'extens':7A,41B,75C 'flaw':3A 'googl':55C 'isol':10A,44B,70C 'let':4A,30B 'leverag':64C 'low':49B,79C 'miss':23B,50C 'prior':57C 'rate':46B 'remot':32B,62C 'runtim':21B 'secur':77C 'sever':48B,78C 'site':9A,43B,69C 'social':35B,65C 'use':34B 'via':71C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Google Chrome older than 157.0.8103.38. Exploitation needs a person to be tricked into installing a crafted extension, so managed browsers that restrict extension installs are less exposed. unknown for any further configuration detail.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"everyone","plain_action":"Update Google Chrome to version 157.0.8103.38 or later, and remove any extensions you do not recognise.","pkeys":[],"ptokens":[],"labels":["chrome","desktopbrowsers","low","runtime"],"campaign_type":null,"first_public_at":"2026-11-03T21:17:36+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121253","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121253","severity":null,"published_at":"2026-11-03T21:17:36+00:00","modified_at":"2026-11-03T21:17:36+00:00","first_seen_at":"2026-11-03T21:19:29+00:00","fetched_at":"2026-11-03T21:19:29+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"}