{"id":"CVE-2026-121031","kind":"vulnerability","aliases":["CVE-2026-121031"],"related":[],"title":"Chrome: PDF viewer flaw lets a crafted extension bypass web origin policy","description":"Missing authorization in PDF in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to bypass web origin policy into a privileged page via a crafted Chrome extension. (Chromium security severity: Medium)","summary":"Google Chrome versions before 157.0.8103.38 have a missing authorization check in the PDF component. A remote attacker can use a crafted Chrome extension to get around web origin policy and reach a privileged page.","severity":"medium","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browser","chrome","desktop","runtime"],"not_affected_if":["chrome-updated","no-malicious-extensions"],"how_to_check":"- Check the installed Chrome version at chrome://settings/help and compare it with `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":"2026-11-03T21:17:06+00:00","first_seen_at":"2026-11-03T21:19:08+00:00","triaged_at":"2026-11-03T21:27:37+00:00","updated_at":"2026-11-03T21:27:37+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-11-03T21:27:37Z","model":"claude-haiku-5-5","output":{"fix":"- Google Chrome: move to `157.0.8103.38` or later.","reach":"internet","title":"Chrome: PDF viewer flaw lets a crafted extension bypass web origin policy","impact":"medium","summary":"Google Chrome versions before 157.0.8103.38 have a missing authorization check in the PDF component. A remote attacker can use a crafted Chrome extension to get around web origin policy and reach a privileged page.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["chrome","browser","desktop"],"confidence":0.6,"fix_status":"available","needs_auth":"unknown","worst_case":"Attacker bypasses web origin policy and reaches privileged browser pages","analyst_note":"","how_to_check":"- Check the installed Chrome version at chrome://settings/help and compare it with `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: Chrome menu > Help > About Google Chrome.","needs_analyst":false,"not_affected_if":["chrome-updated","no-malicious-extensions"],"who_is_affected":"Any desktop browser running Chrome before 157.0.8103.38 is in scope, and the attack depends on a malicious extension being installed. Managed fleets that control extension installation are less exposed. The sources do not say whether mobile Chrome is affected.","user_interaction":"yes","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000683,"input_tokens":4106,"output_tokens":544,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-121031':15A,18A '-2026':14A,17A '157.0.8103.38':27B,66C 'allow':67C 'around':48B 'attack':39B,70C 'author':31B,58C 'browser':19B 'bypass':9A,72C 'check':32B 'chrome':1A,20B,24B,44B,63C,83C 'chromium':85C 'compon':36B 'craft':7A,43B,82C 'cve':13A,16A 'desktop':21B 'extens':8A,45B,84C 'flaw':4A 'get':47B 'googl':23B,62C 'let':5A 'medium':88C 'miss':30B,57C 'origin':11A,50B,74C 'page':56B,79C 'pdf':2A,35B,60C 'polici':12A,51B,75C 'prior':64C 'privileg':55B,78C 'reach':53B 'remot':38B,69C 'runtim':22B 'secur':86C 'sever':87C 'use':41B 'version':25B 'via':80C 'viewer':3A 'web':10A,49B,73C","nicknames":[],"mitigations":[],"who_affected":"Any desktop browser running Chrome before 157.0.8103.38 is in scope, and the attack depends on a malicious extension being installed. Managed fleets that control extension installation are less exposed. The sources do not say whether mobile Chrome is affected.","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: Chrome menu > Help > About Google Chrome.","pkeys":[],"ptokens":[],"labels":["browser","chrome","desktop","medium","runtime"],"campaign_type":null,"first_public_at":"2026-11-03T21:17:06+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121031","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121031","severity":null,"published_at":"2026-11-03T21:17:06+00:00","modified_at":"2026-11-03T21:17:06+00:00","first_seen_at":"2026-11-03T21:19:08+00:00","fetched_at":"2026-11-03T21:19:08+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"}