{"id":"CVE-2026-121134","kind":"vulnerability","aliases":["CVE-2026-121134"],"related":[],"title":"Chrome: BackgroundFetch information loss lets a web page bypass origin policy","description":"Information loss in BackgroundFetch in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to bypass web origin policy via a crafted HTML page. (Chromium security severity: Low)","summary":"A flaw in Chrome's BackgroundFetch feature before 157.0.8103.38 lets a remote attacker bypass web origin policy using a crafted HTML page. The Chromium security severity is rated Low.","severity":"low","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browser-users","chrome","runtime"],"not_affected_if":["chrome-updated"],"how_to_check":"- Check the Chrome version in Chrome's About page or with `chrome://version`\n- Confirm the version is below `157.0.8103.38`","fix":"- Google Chrome: move to `157.0.8103.38` or later","status":"open","published_at":"2026-11-03T21:17:21+00:00","first_seen_at":"2026-11-03T21:19:22+00:00","triaged_at":"2026-11-03T21:24:44+00:00","updated_at":"2026-11-03T21:24:44+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-11-03T21:24:44Z","model":"claude-haiku-5-5","output":{"fix":"- Google Chrome: move to `157.0.8103.38` or later","reach":"internet","title":"Chrome: BackgroundFetch information loss lets a web page bypass origin policy","impact":"medium","summary":"A flaw in Chrome's BackgroundFetch feature before 157.0.8103.38 lets a remote attacker bypass web origin policy using a crafted HTML page. The Chromium security severity is rated Low.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["chrome","browser-users"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"a web page bypasses origin policy and reads cross-site data","analyst_note":"","how_to_check":"- Check the Chrome version in Chrome's About page or with `chrome://version`\n- Confirm the version is below `157.0.8103.38`","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 user running Google Chrome before 157.0.8103.38 who visits a malicious web page can be affected. Servers and managed environments are affected only through the browsers their people use. unknown whether the BackgroundFetch feature must be enabled for exposure.","user_interaction":"yes","needs_special_setup":"unknown","severity_if_unknown":"low"},"cost_usd":0.000659,"input_tokens":4101,"output_tokens":498,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-121134':14A,17A '-2026':13A,16A '157.0.8103.38':31B,61C 'allow':62C 'attack':35B,65C 'backgroundfetch':2A,28B,55C 'browser':19B 'browser-us':18B 'bypass':9A,36B,67C 'chrome':1A,21B,26B,58C 'chromium':46B,76C 'craft':42B,73C 'cve':12A,15A 'featur':29B 'flaw':24B 'googl':57C 'html':43B,74C 'inform':3A,52C 'let':5A,32B 'loss':4A,53C 'low':51B,79C 'origin':10A,38B,69C 'page':8A,44B,75C 'polici':11A,39B,70C 'prior':59C 'rate':50B 'remot':34B,64C 'runtim':22B 'secur':47B,77C 'sever':48B,78C 'use':40B 'user':20B 'via':71C 'web':7A,37B,68C","nicknames":[],"mitigations":[],"who_affected":"Any desktop or mobile user running Google Chrome before 157.0.8103.38 who visits a malicious web page can be affected. Servers and managed environments are affected only through the browsers their people use. unknown whether the BackgroundFetch feature must be enabled for exposure.","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":["browserusers","chrome","low","runtime"],"campaign_type":null,"first_public_at":"2026-11-03T21:17:21+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121134","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121134","severity":null,"published_at":"2026-11-03T21:17:21+00:00","modified_at":"2026-11-03T21:17:22+00:00","first_seen_at":"2026-11-03T21:19:22+00:00","fetched_at":"2026-11-03T21:19:22+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"}