{"id":"CVE-2026-117994","kind":"vulnerability","aliases":["CVE-2026-117994"],"related":[],"title":"Firefox: JavaScript garbage collector use-after-free fixed in 159","description":"Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.","summary":"A use-after-free bug in the JavaScript garbage collector of Firefox can corrupt memory when the engine runs crafted code. The sources do not say what an attacker can gain beyond memory corruption, and the fix ships in Firefox 159 and Firefox ESR 153.6.","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`, and compare it with `159` and `153.6` (ESR)\n- unknown","fix":"- Update Firefox to `159` or Firefox ESR to `153.6`\n- unknown","status":"open","published_at":"2026-10-27T14:16:57+00:00","first_seen_at":"2026-10-27T14:32:25+00:00","triaged_at":"2026-10-27T14:34:55+00:00","updated_at":"2026-10-27T14:34:55+00:00","category":"runtime","confidence":0.4,"triage":{"at":"2026-10-27T14:34:55Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or Firefox ESR to `153.6`\n- unknown","reach":"internet","title":"Firefox: JavaScript garbage collector use-after-free fixed in 159","impact":"medium","summary":"A use-after-free bug in the JavaScript garbage collector of Firefox can corrupt memory when the engine runs crafted code. The sources do not say what an attacker can gain beyond memory corruption, and the fix ships in Firefox 159 and Firefox ESR 153.6.","category":"runtime","nicknames":[],"who_cares":["firefox","browsers","desktop"],"confidence":0.4,"needs_auth":"unknown","worst_case":"unknown","analyst_note":"Check the Mozilla security advisory for this CVE for exploitability, impact and whether it is triggered by visiting a web page.","how_to_check":"- Check the installed Firefox version in Help > About Firefox, or run `firefox --version`, and compare it with `159` and `153.6` (ESR)\n- unknown","needs_analyst":true,"not_affected_if":["already-on-fixed-version"],"who_is_affected":"Anyone running Firefox or Firefox ESR builds older than 159 or 153.6 is affected. The sources do not say which platforms or configurations are most exposed, and they do not say whether embedded uses of the Gecko engine are included.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000581,"input_tokens":3238,"output_tokens":514,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117994':14A,17A '-2026':13A,16A '153.6':67B,87C '159':11A,63B,83C 'attack':51B 'beyond':54B 'browser':18B 'bug':27B 'code':43B 'collector':4A,32B 'compon':76C 'corrupt':36B,56B 'craft':42B 'cve':12A,15A 'desktop':19B 'engin':40B 'esr':66B,86C 'firefox':1A,20B,34B,62B,65B,82C,85C 'fix':9A,59B,80C 'free':8A,26B,71C 'gain':53B 'garbag':3A,31B 'gc':75C 'javascript':2A,30B,74C 'memori':37B,55B 'run':41B 'runtim':21B 'say':48B 'ship':60B 'sourc':45B 'use':6A,24B,69C 'use-after-fre':5A,23B,68C 'vulner':78C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox or Firefox ESR builds older than 159 or 153.6 is affected. The sources do not say which platforms or configurations are most exposed, and they do not say whether embedded uses of the Gecko engine are included.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:57+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117994","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117994","severity":null,"published_at":"2026-10-27T14:16:57+00:00","modified_at":"2026-10-27T14:16:57+00:00","first_seen_at":"2026-10-27T14:32:25+00:00","fetched_at":"2026-10-27T14:32:25+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"}