{"id":"CVE-2026-124863","kind":"vulnerability","aliases":["CVE-2026-124863"],"related":[],"title":"Firefox: use-after-free in HTML parser can crash or be exploited","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":"Firefox's HTML parser frees memory that is still referenced, a use-after-free bug. The sources do not say what an attacker can achieve beyond memory corruption.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browsers","desktop","firefox","runtime"],"not_affected_if":["up-to-date-firefox"],"how_to_check":"- Check the Firefox version with Help > About Firefox, or `firefox --version`\n- Compare it against the fixed versions: Firefox 160, Firefox ESR 115.45, Firefox ESR 153.7","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":"2026-11-10T14:22:14+00:00","triaged_at":"2026-11-10T14:26:33+00:00","updated_at":"2026-11-10T14:26:33+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-11-10T14:26:33Z","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 can crash or be exploited","impact":"high","summary":"Firefox's HTML parser frees memory that is still referenced, a use-after-free bug. The sources do not say what an attacker can achieve beyond memory corruption.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["firefox","browsers","desktop"],"confidence":0.6,"fix_status":"available","needs_auth":"unknown","worst_case":"unknown; memory corruption in the browser, possibly code execution","analyst_note":"Check the Mozilla security advisory for this CVE to confirm trigger conditions, whether exploitation requires user interaction, and the real impact.","how_to_check":"- Check the Firefox version with Help > About Firefox, or `firefox --version`\n- Compare it against the fixed versions: Firefox 160, Firefox ESR 115.45, Firefox ESR 153.7","plain_action":"Update Firefox to version 160, or ESR 115.45 or 153.7 if you use the ESR channel, through Firefox's own update prompt or Help > About Firefox.","product_name":"","needs_analyst":true,"not_affected_if":["up-to-date-firefox"],"who_is_affected":"Anyone running Firefox or Firefox ESR builds older than the fixed versions. The sources do not describe a specific page or configuration that triggers the flaw, so it is unknown whether a remote page alone is enough.","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000744,"input_tokens":4490,"output_tokens":591,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-124863':16A,19A '-2026':15A,18A '115.45':72C '153.7':76C '160':69C 'achiev':49B 'attack':47B 'beyond':50B 'browser':20B 'bug':39B 'compon':62C 'corrupt':52B 'crash':10A 'cve':14A,17A 'desktop':21B 'dom':59C 'esr':71C,75C 'exploit':13A 'firefox':1A,22B,24B,68C,70C,74C 'fix':66C 'free':5A,28B,38B,56C 'html':7A,26B,60C 'memori':29B,51B 'parser':8A,27B,61C 'referenc':33B 'runtim':23B 'say':44B 'sourc':41B 'still':32B 'use':3A,36B,54C 'use-after-fre':2A,35B,53C 'vulner':64C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox or Firefox ESR builds older than the fixed versions. The sources do not describe a specific page or configuration that triggers the flaw, so it is unknown whether a remote page alone is enough.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"everyone","plain_action":"Update Firefox to version 160, or ESR 115.45 or 153.7 if you use the ESR channel, through Firefox's own update prompt or Help > About Firefox.","pkeys":[],"ptokens":[],"labels":["browsers","desktop","firefox","runtime","unknown"],"campaign_type":null,"search_a":"'-124863':16A,19A '-2026':15A,18A 'crash':10A 'cve':14A,17A 'exploit':13A 'firefox':1A 'free':5A 'html':7A 'parser':8A 'use':3A 'use-after-fre':2A","search_b":"'achiev':49B 'attack':47B 'beyond':50B 'browser':20B 'bug':39B 'corrupt':52B 'desktop':21B 'firefox':22B,24B 'free':28B,38B 'html':26B 'memori':29B,51B 'parser':27B 'referenc':33B 'runtim':23B 'say':44B 'sourc':41B 'still':32B 'use':36B 'use-after-fre':35B","search_c":"'115.45':72C '153.7':76C '160':69C 'compon':62C 'dom':59C 'esr':71C,75C 'firefox':68C,70C,74C 'fix':66C 'free':56C 'html':60C 'parser':61C 'use':54C 'use-after-fre':53C 'vulner':64C","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-2026-124863","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-124863","severity":null,"published_at":"2026-11-10T14:17:18+00:00","modified_at":"2026-11-10T14:17:18+00:00","first_seen_at":"2026-11-10T14:22:14+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"}