{"id":"CVE-2026-124858","kind":"vulnerability","aliases":["CVE-2026-124858"],"related":[],"title":"Firefox: use-after-free in HTML parser lets attacker run code","description":"Use-after-free in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 160, Firefox ESR 115.45, and Firefox ESR 153.7.","summary":"A use-after-free bug in the DOM HTML Parser component of Firefox can corrupt memory when a page is processed. The sources do not state what an attacker can get beyond that, so the impact is unconfirmed.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browser","desktop","firefox","runtime"],"not_affected_if":["fixed-version"],"how_to_check":"- Check the installed Firefox version in Help > About Firefox\n- Firefox versions below `160`, `115.45` (ESR 115), or `153.7` (ESR 153) are affected per the description","fix":"- Firefox `160`\n- Firefox ESR `115.45`\n- Firefox ESR `153.7`","status":"open","published_at":"2026-11-10T14:17:18+00:00","first_seen_at":"2026-11-10T14:22:13+00:00","triaged_at":"2026-11-10T14:26:40+00:00","updated_at":"2026-11-10T14:26:40+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-11-10T14:26:40Z","model":"claude-haiku-5-5","output":{"fix":"- Firefox `160`\n- Firefox ESR `115.45`\n- Firefox ESR `153.7`","reach":"internet","title":"Firefox: use-after-free in HTML parser lets attacker run code","impact":"high","summary":"A use-after-free bug in the DOM HTML Parser component of Firefox can corrupt memory when a page is processed. The sources do not state what an attacker can get beyond that, so the impact is unconfirmed.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["firefox","browser","desktop"],"confidence":0.5,"fix_status":"available","needs_auth":"no","worst_case":"unknown; memory corruption may let web content run code","analyst_note":"Confirm from Mozilla's advisory whether this is exploitable from web content, the exploit status, and the CVE's exact severity.","how_to_check":"- Check the installed Firefox version in Help > About Firefox\n- Firefox versions below `160`, `115.45` (ESR 115), or `153.7` (ESR 153) are affected per the description","plain_action":"Update Firefox to version 160 or later, or to the matching ESR release 115.45 or 153.7.","product_name":"","needs_analyst":true,"not_affected_if":["fixed-version"],"who_is_affected":"Anyone running an affected desktop Firefox release, including ESR branches, who browses web pages. The sources do not describe a special configuration or required account, so default installs are likely exposed.","user_interaction":"yes","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000722,"input_tokens":4490,"output_tokens":546,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-124858':15A,18A '-2026':14A,17A '115.45':81C '153.7':85C '160':78C 'attack':10A,52B 'beyond':55B 'browser':19B 'bug':28B 'code':12A 'compon':34B,71C 'corrupt':38B 'cve':13A,16A 'desktop':20B 'dom':31B,68C 'esr':80C,84C 'firefox':1A,21B,36B,77C,79C,83C 'fix':75C 'free':5A,27B,65C 'get':54B 'html':7A,32B,69C 'impact':59B 'let':9A 'memori':39B 'page':42B 'parser':8A,33B,70C 'process':44B 'run':11A 'runtim':22B 'sourc':46B 'state':49B 'unconfirm':61B 'use':3A,25B,63C 'use-after-fre':2A,24B,62C 'vulner':73C","nicknames":[],"mitigations":[],"who_affected":"Anyone running an affected desktop Firefox release, including ESR branches, who browses web pages. The sources do not describe a special configuration or required account, so default installs are likely exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"everyone","plain_action":"Update Firefox to version 160 or later, or to the matching ESR release 115.45 or 153.7.","pkeys":[],"ptokens":[],"labels":["browser","desktop","firefox","runtime","unknown"],"campaign_type":null,"search_a":"'-124858':15A,18A '-2026':14A,17A 'attack':10A 'code':12A 'cve':13A,16A 'firefox':1A 'free':5A 'html':7A 'let':9A 'parser':8A 'run':11A 'use':3A 'use-after-fre':2A","search_b":"'attack':52B 'beyond':55B 'browser':19B 'bug':28B 'compon':34B 'corrupt':38B 'desktop':20B 'dom':31B 'firefox':21B,36B 'free':27B 'get':54B 'html':32B 'impact':59B 'memori':39B 'page':42B 'parser':33B 'process':44B 'runtim':22B 'sourc':46B 'state':49B 'unconfirm':61B 'use':25B 'use-after-fre':24B","search_c":"'115.45':81C '153.7':85C '160':78C 'compon':71C 'dom':68C 'esr':80C,84C 'firefox':77C,79C,83C 'fix':75C 'free':65C 'html':69C 'parser':70C 'use':63C 'use-after-fre':62C 'vulner':73C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T14:17:18+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-124858","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-124858","severity":null,"published_at":"2026-11-10T14:17:18+00:00","modified_at":"2026-11-10T14:17:18+00:00","first_seen_at":"2026-11-10T14:22:13+00:00","fetched_at":"2026-11-10T14:22:13+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"}