{"id":"CVE-2026-117963","kind":"vulnerability","aliases":["CVE-2026-117963"],"related":[],"title":"Firefox: service worker boundary bug fixed in versions 159 and ESR 153.6","description":"Incorrect boundary conditions in the DOM: Service Workers component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.","summary":"Firefox's Service Workers component has an incorrect boundary condition in the DOM code. The sources do not say what an attacker gets from it.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browsers","desktop","firefox","runtime"],"not_affected_if":["already-on-fixed-version"],"how_to_check":"- Check the installed Firefox version in Help > About Firefox, or run `firefox --version`\n- Check whether the browser is a Firefox ESR build below `153.6`","fix":"- Update Firefox to `159` or later, or Firefox ESR to `153.6` or later","status":"open","published_at":"2026-10-27T14:16:52+00:00","first_seen_at":"2026-10-27T14:32:24+00:00","triaged_at":"2026-10-27T14:35:25+00:00","updated_at":"2026-10-27T14:35:25+00:00","category":"runtime","confidence":0.4,"triage":{"at":"2026-10-27T14:35:25Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later, or Firefox ESR to `153.6` or later","reach":"internet","title":"Firefox: service worker boundary bug fixed in versions 159 and ESR 153.6","impact":"medium","summary":"Firefox's Service Workers component has an incorrect boundary condition in the DOM code. The sources do not say what an attacker gets from it.","category":"runtime","nicknames":[],"who_cares":["firefox","browsers","desktop"],"confidence":0.4,"needs_auth":"unknown","worst_case":"unknown; the sources do not describe the impact","analyst_note":"Check the Mozilla security advisory for this CVE to learn the impact and trigger conditions; the NVD entry gives none.","how_to_check":"- Check the installed Firefox version in Help > About Firefox, or run `firefox --version`\n- Check whether the browser is a Firefox ESR build below `153.6`","needs_analyst":true,"not_affected_if":["already-on-fixed-version"],"who_is_affected":"Anyone running Firefox or Firefox ESR older than the fixed versions is in scope. The sources do not say which configurations or sites trigger the flaw.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000552,"input_tokens":3250,"output_tokens":454,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117963':15A,18A '-2026':14A,17A '153.6':12A,65C '159':9A,61C 'attack':44B 'boundari':4A,31B,47C 'browser':19B 'bug':5A 'code':36B 'compon':27B,54C 'condit':32B,48C 'cve':13A,16A 'desktop':20B 'dom':35B,51C 'esr':11A,64C 'firefox':1A,21B,23B,60C,63C 'fix':6A,58C 'get':45B 'incorrect':30B,46C 'runtim':22B 'say':41B 'servic':2A,25B,52C 'sourc':38B 'version':8A 'vulner':56C 'worker':3A,26B,53C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox or Firefox ESR older than the fixed versions is in scope. The sources do not say which configurations or sites trigger the flaw.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:52+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117963","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117963","severity":null,"published_at":"2026-10-27T14:16:52+00:00","modified_at":"2026-10-27T14:16:52+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"}