{"id":"CVE-2026-117936","kind":"vulnerability","aliases":["CVE-2026-117936"],"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 reuses memory after it has been freed. The sources do not say what an attacker gains beyond that, so the impact is not confirmed.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browsers","desktop","firefox","runtime"],"not_affected_if":["already-updated"],"how_to_check":"- Check the installed Firefox version in the browser's About page or with `firefox --version`.\n- Compare it against the fixed releases: Firefox `159`, Firefox ESR `115.44`, or Firefox ESR `153.6`.\n- Check whether Firefox ESR is in use on managed machines through the fleet's software inventory.","fix":"- Update Firefox to `159` or later.\n- Update Firefox ESR 115 to `115.44` or later.\n- Update Firefox ESR 153 to `153.6` or later.","status":"open","published_at":"2026-10-27T14:16:49+00:00","first_seen_at":"2026-10-27T14:32:23+00:00","triaged_at":"2026-10-27T14:37:02+00:00","updated_at":"2026-10-27T14:37:02+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-27T14:37:02Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later.\n- Update Firefox ESR 115 to `115.44` or later.\n- Update Firefox ESR 153 to `153.6` or later.","reach":"unknown","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 reuses memory after it has been freed. The sources do not say what an attacker gains beyond that, so the impact is not confirmed.","category":"runtime","nicknames":[],"who_cares":["firefox","browsers","desktop"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown; the sources do not state the attacker's gain","analyst_note":"Confirm the attack trigger and worst-case impact from the Mozilla security advisory for the Firefox 159 and ESR fix release notes; the NVD entry gives no details.","how_to_check":"- Check the installed Firefox version in the browser's About page or with `firefox --version`.\n- Compare it against the fixed releases: Firefox `159`, Firefox ESR `115.44`, or Firefox ESR `153.6`.\n- Check whether Firefox ESR is in use on managed machines through the fleet's software inventory.","needs_analyst":true,"not_affected_if":["already-updated"],"who_is_affected":"Any machine running Firefox or Firefox ESR older than the fixed versions is exposed, since the flaw is in the browser's DOM code. The sources do not describe a server-side path or special configuration, so the exact trigger conditions are unknown. Systems on the fixed versions can skip it.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000633,"input_tokens":3254,"output_tokens":615,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117936':17A,20A '-2026':16A,19A '115.44':82C '153.6':86C '159':79C 'attack':12A,53B 'beyond':55B 'browser':21B 'bug':30B 'code':14A 'compon':38B,72C 'confirm':62B 'core':8A,35B,70C 'cve':15A,18A 'desktop':22B 'dom':7A,34B,69C 'esr':81C,85C 'firefox':1A,23B,33B,78C,80C,84C 'fix':76C 'free':5A,29B,66C 'freed':45B 'gain':54B 'html':10A,37B,71C 'impact':59B 'let':11A 'memori':40B 'reus':39B 'run':13A 'runtim':24B 'say':50B 'sourc':47B 'use':3A,27B,64C 'use-after-fre':2A,26B,63C 'vulner':74C","nicknames":[],"mitigations":[],"who_affected":"Any machine running Firefox or Firefox ESR older than the fixed versions is exposed, since the flaw is in the browser's DOM code. The sources do not describe a server-side path or special configuration, so the exact trigger conditions are unknown. Systems on the fixed versions can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:49+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117936","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117936","severity":null,"published_at":"2026-10-27T14:16:49+00:00","modified_at":"2026-10-27T14:16:49+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"}