{"id":"CVE-2026-121161","kind":"vulnerability","aliases":["CVE-2026-121161"],"related":[],"title":"Chrome: BackgroundFetch flaw leaks cross-origin data from a crafted page","description":"Information leak in BackgroundFetch in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to obtain cross-origin data via a crafted HTML page. (Chromium security severity: Medium)","summary":"A flaw in the BackgroundFetch feature of Google Chrome lets a crafted HTML page read cross-origin data it should not reach. Chromium rates it Medium severity.","severity":"medium","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browsers","chrome","end-users","runtime"],"not_affected_if":["chrome-up-to-date"],"how_to_check":"- Check the Chrome version in Chrome's About page or with `chrome://version`\n- Confirm whether the installed version is earlier than `157.0.8103.38`","fix":"- Google Chrome: move to `157.0.8103.38` or later","status":"open","published_at":"2026-11-03T21:17:23+00:00","first_seen_at":"2026-11-03T21:19:23+00:00","triaged_at":"2026-11-03T21:23:27+00:00","updated_at":"2026-11-03T21:23:27+00:00","category":"runtime","confidence":0.8,"triage":{"at":"2026-11-03T21:23:27Z","model":"claude-haiku-5-5","output":{"fix":"- Google Chrome: move to `157.0.8103.38` or later","reach":"internet","title":"Chrome: BackgroundFetch flaw leaks cross-origin data from a crafted page","impact":"medium","summary":"A flaw in the BackgroundFetch feature of Google Chrome lets a crafted HTML page read cross-origin data it should not reach. Chromium rates it Medium severity.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["chrome","browsers","end-users"],"confidence":0.8,"fix_status":"available","needs_auth":"no","worst_case":"Cross-origin data from other sites is readable by a malicious page","analyst_note":"","how_to_check":"- Check the Chrome version in Chrome's About page or with `chrome://version`\n- Confirm whether the installed version is earlier than `157.0.8103.38`","plain_action":"Update Google Chrome to version 157.0.8103.38 or later.","needs_analyst":false,"not_affected_if":["chrome-up-to-date"],"who_is_affected":"Anyone running Google Chrome before 157.0.8103.38 who visits a web page that could be crafted by an attacker. Managed or enterprise Chrome fleets should check their versions. Other Chromium-based browsers may carry the same flaw depending on their own update schedules, which the sources do not cover.","user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"medium"},"cost_usd":0.000666,"input_tokens":4102,"output_tokens":512,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-121161':15A,18A '-2026':14A,17A '157.0.8103.38':62C 'allow':63C 'attack':66C 'backgroundfetch':2A,29B,56C 'browser':19B 'chrome':1A,20B,33B,59C 'chromium':48B,78C 'craft':11A,36B,75C 'cross':6A,41B,70C 'cross-origin':5A,40B,69C 'cve':13A,16A 'data':8A,43B,72C 'end':22B 'end-us':21B 'featur':30B 'flaw':3A,26B 'googl':32B,58C 'html':37B,76C 'inform':53C 'leak':4A,54C 'let':34B 'medium':51B,81C 'obtain':68C 'origin':7A,42B,71C 'page':12A,38B,77C 'prior':60C 'rate':49B 'reach':47B 'read':39B 'remot':65C 'runtim':24B 'secur':79C 'sever':52B,80C 'user':23B 'via':73C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Google Chrome before 157.0.8103.38 who visits a web page that could be crafted by an attacker. Managed or enterprise Chrome fleets should check their versions. Other Chromium-based browsers may carry the same flaw depending on their own update schedules, which the sources do not cover.","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","endusers","medium","runtime"],"campaign_type":null,"first_public_at":"2026-11-03T21:17:23+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121161","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121161","severity":null,"published_at":"2026-11-03T21:17:23+00:00","modified_at":"2026-11-03T21:17:24+00:00","first_seen_at":"2026-11-03T21:19:23+00:00","fetched_at":"2026-11-03T21:19:23+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"}