{"id":"CVE-2026-121242","kind":"vulnerability","aliases":["CVE-2026-121242"],"related":[],"title":"Chrome: WebPackaging input validation lets remote sites bypass origin policy","description":"Improper input validation in WebPackaging in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to bypass web origin policy via crafted network traffic. (Chromium security severity: Medium)","summary":"Google Chrome before 157.0.8103.38 mishandles input in its WebPackaging feature, so crafted network traffic can bypass web origin policy. An attacker who lures a user to a malicious page could read or act on content from another site.","severity":"medium","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browsers","chrome","desktop","mobile","runtime"],"not_affected_if":["chrome-updated"],"how_to_check":"- Open Chrome, go to `chrome://settings/help` and read the installed version\n- Compare against `157.0.8103.38`; anything older is in range","fix":"- Google Chrome: `157.0.8103.38`","status":"open","published_at":"2026-11-03T21:17:34+00:00","first_seen_at":"2026-11-03T21:19:29+00:00","triaged_at":"2026-11-03T21:21:08+00:00","updated_at":"2026-11-03T21:21:08+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-11-03T21:21:08Z","model":"claude-haiku-5-5","output":{"fix":"- Google Chrome: `157.0.8103.38`","reach":"internet","title":"Chrome: WebPackaging input validation lets remote sites bypass origin policy","impact":"medium","summary":"Google Chrome before 157.0.8103.38 mishandles input in its WebPackaging feature, so crafted network traffic can bypass web origin policy. An attacker who lures a user to a malicious page could read or act on content from another site.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["chrome","browsers","desktop","mobile"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"cross-origin content readable or actions taken on another site","analyst_note":"","how_to_check":"- Open Chrome, go to `chrome://settings/help` and read the installed version\n- Compare against `157.0.8103.38`; anything older is in range","plain_action":"Update Google Chrome to version 157.0.8103.38 or later.","needs_analyst":false,"not_affected_if":["chrome-updated"],"who_is_affected":"Any desktop or mobile Chrome install older than 157.0.8103.38 is exposed when it loads attacker-controlled network content. Browsing only trusted sites reduces but does not remove the risk. unknown whether non-default WebPackaging use is required, as the sources do not say.","user_interaction":"yes","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000664,"input_tokens":4097,"output_tokens":509,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-121242':13A,16A '-2026':12A,15A '157.0.8103.38':25B,70C 'act':54B 'allow':71C 'anoth':58B 'attack':42B,74C 'browser':17B 'bypass':8A,37B,76C 'chrome':1A,18B,23B,67C 'chromium':84C 'content':56B 'could':51B 'craft':33B,81C 'cve':11A,14A 'desktop':19B 'featur':31B 'googl':22B,66C 'improp':60C 'input':3A,27B,61C 'let':5A 'lure':44B 'malici':49B 'medium':87C 'mishandl':26B 'mobil':20B 'network':34B,82C 'origin':9A,39B,78C 'page':50B 'polici':10A,40B,79C 'prior':68C 'read':52B 'remot':6A,73C 'runtim':21B 'secur':85C 'sever':86C 'site':7A,59B 'traffic':35B,83C 'user':46B 'valid':4A,62C 'via':80C 'web':38B,77C 'webpackag':2A,30B,64C","nicknames":[],"mitigations":[],"who_affected":"Any desktop or mobile Chrome install older than 157.0.8103.38 is exposed when it loads attacker-controlled network content. Browsing only trusted sites reduces but does not remove the risk. unknown whether non-default WebPackaging use is required, as the sources do not say.","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.","pkeys":[],"ptokens":[],"labels":["browsers","chrome","desktop","medium","mobile","runtime"],"campaign_type":null,"first_public_at":"2026-11-03T21:17:34+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121242","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121242","severity":null,"published_at":"2026-11-03T21:17:34+00:00","modified_at":"2026-11-03T21:17:34+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"}