{"id":"CVE-2026-117966","kind":"vulnerability","aliases":["CVE-2026-117966"],"related":[],"title":"Firefox: site isolation flaw in HTTP networking component fixed","description":"Site isolation issue in the Networking: HTTP component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.","summary":"Mozilla fixed a site isolation issue in the Networking HTTP component of Firefox in versions 159, ESR 115.44 and ESR 153.6. The sources do not describe what an attacker can read or do through it.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["desktop-browsers","firefox","other"],"not_affected_if":[],"how_to_check":"- Run `firefox --version` or check Help > About Firefox and compare against `159`, `115.44` (ESR) or `153.6` (ESR)\n- unknown for any other check, since the sources do not say","fix":"- Update Firefox to `159`, or ESR to `115.44` or `153.6`","status":"open","published_at":"2026-10-27T14:16:54+00:00","first_seen_at":"2026-10-27T14:32:24+00:00","triaged_at":"2026-10-27T14:35:23+00:00","updated_at":"2026-10-27T14:35:23+00:00","category":"other","confidence":0.5,"triage":{"at":"2026-10-27T14:35:23Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159`, or ESR to `115.44` or `153.6`","reach":"unknown","title":"Firefox: site isolation flaw in HTTP networking component fixed","impact":"medium","summary":"Mozilla fixed a site isolation issue in the Networking HTTP component of Firefox in versions 159, ESR 115.44 and ESR 153.6. The sources do not describe what an attacker can read or do through it.","category":"other","nicknames":[],"who_cares":["firefox","desktop-browsers"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown; site isolation bypass may let a malicious site read other sites' data","analyst_note":"Check the Mozilla Foundation security advisory for CVE-2026-117966 to confirm the impact, trigger conditions and whether it is exploited.","how_to_check":"- Run `firefox --version` or check Help > About Firefox and compare against `159`, `115.44` (ESR) or `153.6` (ESR)\n- unknown for any other check, since the sources do not say","needs_analyst":true,"not_affected_if":[],"who_is_affected":"unknown. The sources name only Firefox versions; they do not say which configurations or user actions are needed to trigger the flaw.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000565,"input_tokens":3252,"output_tokens":480,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117966':12A,15A '-2026':11A,14A '115.44':37B,68C '153.6':40B,72C '159':35B,65C 'attack':48B 'browser':18B 'compon':8A,30B,58C 'cve':10A,13A 'describ':45B 'desktop':17B 'desktop-brows':16B 'esr':36B,39B,67C,71C 'firefox':1A,19B,32B,64C,66C,70C 'fix':9A,21B,62C 'flaw':4A 'http':6A,29B,57C 'isol':3A,24B,52C 'issu':25B,53C 'mozilla':20B 'network':7A,28B,56C 'read':50B 'site':2A,23B,51C 'sourc':42B 'version':34B 'vulner':60C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:54+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117966","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117966","severity":null,"published_at":"2026-10-27T14:16:54+00:00","modified_at":"2026-10-27T14:16:54+00:00","first_seen_at":"2026-10-27T14:32:24+00:00","fetched_at":"2026-10-27T14:32:24+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"}