{"id":"CVE-2026-117929","kind":"vulnerability","aliases":["CVE-2026-117929"],"related":[],"title":"Firefox: use-after-free in DOM core and HTML lets attackers run code","description":"Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.","summary":"A use-after-free bug in the Firefox DOM Core and HTML component lets memory that was already released be reused. The sources do not say what an attacker gets beyond that, so the reach and impact below are unconfirmed.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browsers","desktop","firefox","firefox-esr","runtime"],"not_affected_if":["already-patched-versions"],"how_to_check":"- Run `firefox --version` or check Help > About Firefox and compare with the fixed versions\n- Check Firefox ESR installs for `115.44` or `153.6`, or a newer build","fix":"- Update Firefox to `159` or later\n- Update Firefox ESR to `115.44` or `153.6` or later","status":"open","published_at":"2026-10-27T14:16:48+00:00","first_seen_at":"2026-10-27T14:32:23+00:00","triaged_at":"2026-10-27T14:37:09+00:00","updated_at":"2026-10-27T14:37:09+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-27T14:37:09Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later\n- Update Firefox ESR to `115.44` or `153.6` or later","reach":"internet","title":"Firefox: use-after-free in DOM core and HTML lets attackers run code","impact":"high","summary":"A use-after-free bug in the Firefox DOM Core and HTML component lets memory that was already released be reused. The sources do not say what an attacker gets beyond that, so the reach and impact below are unconfirmed.","category":"runtime","nicknames":[],"who_cares":["firefox","firefox-esr","desktop","browsers"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown; sources do not say what an attacker gets","analyst_note":"Check the Mozilla security advisory for this CVE to confirm the trigger, exploitability and impact.","how_to_check":"- Run `firefox --version` or check Help > About Firefox and compare with the fixed versions\n- Check Firefox ESR installs for `115.44` or `153.6`, or a newer build","needs_analyst":true,"not_affected_if":["already-patched-versions"],"who_is_affected":"Anyone running Firefox builds before the fixed versions, including Firefox ESR 115 and ESR 153 lines, is exposed. The sources do not say which page or content triggers the bug, so unknown whether a plain web visit is enough. Teams that only use managed, auto-updated browsers are likely covered once updates land.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000597,"input_tokens":3254,"output_tokens":543,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117929':17A,20A '-2026':16A,19A '115.44':88C '153.6':92C '159':85C 'alreadi':46B 'attack':12A,57B 'beyond':59B 'browser':21B 'bug':33B 'code':14A 'compon':41B,78C 'core':8A,38B,76C 'cve':15A,18A 'desktop':22B 'dom':7A,37B,75C 'esr':26B,87C,91C 'firefox':1A,23B,25B,36B,84C,86C,90C 'firefox-esr':24B 'fix':82C 'free':5A,32B,72C 'get':58B 'html':10A,40B,77C 'impact':65B 'let':11A,42B 'memori':43B 'reach':63B 'releas':47B 'reus':49B 'run':13A 'runtim':27B 'say':54B 'sourc':51B 'unconfirm':68B 'use':3A,30B,70C 'use-after-fre':2A,29B,69C 'vulner':80C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox builds before the fixed versions, including Firefox ESR 115 and ESR 153 lines, is exposed. The sources do not say which page or content triggers the bug, so unknown whether a plain web visit is enough. Teams that only use managed, auto-updated browsers are likely covered once updates land.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:48+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117929","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117929","severity":null,"published_at":"2026-10-27T14:16:48+00:00","modified_at":"2026-10-27T14:16:48+00:00","first_seen_at":"2026-10-27T14:32:23+00:00","fetched_at":"2026-10-27T14:32:23+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"}