{"id":"CVE-2026-124871","kind":"vulnerability","aliases":["CVE-2026-124871"],"related":[],"title":"Firefox: use-after-free in the HTML parser can crash or run code","description":"Use-after-free in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 160.","summary":"A use-after-free bug in Firefox's DOM HTML Parser component lets memory be reused after it is freed. The sources do not say what an attacker can achieve beyond that.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browser","firefox","runtime"],"not_affected_if":["firefox-160-or-newer"],"how_to_check":"- Run Firefox and open Help > About Firefox to read the installed version.\n- Check that the version is `160` or newer.","fix":"- Firefox: `160`","status":"open","published_at":"2026-11-10T14:17:19+00:00","first_seen_at":"2026-11-10T14:22:14+00:00","triaged_at":"2026-11-10T14:26:22+00:00","updated_at":"2026-11-10T14:26:22+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-11-10T14:26:22Z","model":"claude-haiku-5-5","output":{"fix":"- Firefox: `160`","reach":"internet","title":"Firefox: use-after-free in the HTML parser can crash or run code","impact":"high","summary":"A use-after-free bug in Firefox's DOM HTML Parser component lets memory be reused after it is freed. The sources do not say what an attacker can achieve beyond that.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["firefox","browser"],"confidence":0.5,"fix_status":"available","needs_auth":"unknown","worst_case":"unknown; memory corruption may allow code execution","analyst_note":"Confirm from Mozilla's Firefox 160 security advisory whether this CVE is exploitable from web content and what the attacker gets.","how_to_check":"- Run Firefox and open Help > About Firefox to read the installed version.\n- Check that the version is `160` or newer.","plain_action":"Update Firefox to version 160 or newer: Menu > Help > About Firefox.","product_name":"","needs_analyst":true,"not_affected_if":["firefox-160-or-newer"],"who_is_affected":"Anyone running Firefox older than version 160 is affected, since the flaw is in the browser's HTML parser and is reached by loading web pages. The sources do not say whether a user must visit a malicious page or whether any other setting matters.","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000695,"input_tokens":4465,"output_tokens":496,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-124871':17A,20A '-2026':16A,19A '160':72C 'achiev':54B 'attack':52B 'beyond':55B 'browser':21B 'bug':29B 'code':14A 'compon':36B,65C 'crash':11A 'cve':15A,18A 'dom':33B,62C 'firefox':1A,22B,31B,71C 'fix':69C 'free':5A,28B,59C 'freed':44B 'html':8A,34B,63C 'let':37B 'memori':38B 'parser':9A,35B,64C 'reus':40B 'run':13A 'runtim':23B 'say':49B 'sourc':46B 'use':3A,26B,57C 'use-after-fre':2A,25B,56C 'vulner':67C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox older than version 160 is affected, since the flaw is in the browser's HTML parser and is reached by loading web pages. The sources do not say whether a user must visit a malicious page or whether any other setting matters.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"everyone","plain_action":"Update Firefox to version 160 or newer: Menu > Help > About Firefox.","pkeys":[],"ptokens":[],"labels":["browser","firefox","runtime","unknown"],"campaign_type":null,"search_a":"'-124871':17A,20A '-2026':16A,19A 'code':14A 'crash':11A 'cve':15A,18A 'firefox':1A 'free':5A 'html':8A 'parser':9A 'run':13A 'use':3A 'use-after-fre':2A","search_b":"'achiev':54B 'attack':52B 'beyond':55B 'browser':21B 'bug':29B 'compon':36B 'dom':33B 'firefox':22B,31B 'free':28B 'freed':44B 'html':34B 'let':37B 'memori':38B 'parser':35B 'reus':40B 'runtim':23B 'say':49B 'sourc':46B 'use':26B 'use-after-fre':25B","search_c":"'160':72C 'compon':65C 'dom':62C 'firefox':71C 'fix':69C 'free':59C 'html':63C 'parser':64C 'use':57C 'use-after-fre':56C 'vulner':67C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T14:17:19+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-124871","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-124871","severity":null,"published_at":"2026-11-10T14:17:19+00:00","modified_at":"2026-11-10T14:17:19+00:00","first_seen_at":"2026-11-10T14:22:14+00:00","fetched_at":"2026-11-10T14:22:14+00:00","note":null}],"documents":[],"disclosures":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}