{"id":"CVE-2026-124889","kind":"vulnerability","aliases":["CVE-2026-124889"],"related":[],"title":"Firefox: CSS parsing use-after-free could let a page run code","description":"Use-after-free in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.","summary":"A use-after-free bug in Firefox's CSS Parsing and Computation component lets memory be reused after it is freed. The sources do not state what an attacker can do beyond that, so the impact is not confirmed.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browser","firefox","runtime"],"not_affected_if":["firefox-160-or-later","firefox-esr-153.7-or-later"],"how_to_check":"- Check the Firefox version under Help > About Firefox, or `firefox --version` on the command line.\n- Compare it against the fixed versions named in the sources: Firefox 160 and Firefox ESR 153.7.","fix":"- Firefox: `160` or later.\n- Firefox ESR: `153.7` or later.","status":"open","published_at":"2026-11-10T14:17:22+00:00","first_seen_at":"2026-11-10T14:22:15+00:00","triaged_at":"2026-11-10T14:26:03+00:00","updated_at":"2026-11-10T14:26:03+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-11-10T14:26:03Z","model":"claude-haiku-5-5","output":{"fix":"- Firefox: `160` or later.\n- Firefox ESR: `153.7` or later.","reach":"unknown","title":"Firefox: CSS parsing use-after-free could let a page run code","impact":"high","summary":"A use-after-free bug in Firefox's CSS Parsing and Computation component lets memory be reused after it is freed. The sources do not state what an attacker can do beyond that, so the impact is not confirmed.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["firefox","browser"],"confidence":0.5,"fix_status":"available","needs_auth":"unknown","worst_case":"unknown; memory corruption could allow code execution","analyst_note":"Confirm the trigger (whether a malicious web page suffices) and the exploitation impact from the Mozilla advisory for CVE-2026-124889.","how_to_check":"- Check the Firefox version under Help > About Firefox, or `firefox --version` on the command line.\n- Compare it against the fixed versions named in the sources: Firefox 160 and Firefox ESR 153.7.","plain_action":"Update Firefox to version 160 or later (or Firefox ESR 153.7 or later) from Help > About Firefox.","product_name":"","needs_analyst":true,"not_affected_if":["firefox-160-or-later","firefox-esr-153.7-or-later"],"who_is_affected":"Anyone running Firefox before the fixed versions named in the sources. The sources do not say whether the bug is reachable from ordinary web browsing or needs special conditions. unknown for the exact trigger.","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.00074,"input_tokens":4480,"output_tokens":583,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-124889':16A,19A '-2026':15A,18A '153.7':84C '160':80C 'attack':52B 'beyond':55B 'browser':20B 'bug':28B 'code':13A 'compon':36B,73C 'comput':35B,72C 'confirm':62B 'could':8A 'css':2A,32B,69C 'cve':14A,17A 'esr':83C 'firefox':1A,21B,30B,79C,82C 'fix':77C 'free':7A,27B,66C 'freed':44B 'impact':59B 'let':9A,37B 'memori':38B 'page':11A 'pars':3A,33B,70C 'reus':40B 'run':12A 'runtim':22B 'sourc':46B 'state':49B 'use':5A,25B,64C 'use-after-fre':4A,24B,63C 'vulner':75C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox before the fixed versions named in the sources. The sources do not say whether the bug is reachable from ordinary web browsing or needs special conditions. unknown for the exact trigger.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"everyone","plain_action":"Update Firefox to version 160 or later (or Firefox ESR 153.7 or later) from Help > About Firefox.","pkeys":[],"ptokens":[],"labels":["browser","firefox","runtime","unknown"],"campaign_type":null,"search_a":"'-124889':16A,19A '-2026':15A,18A 'code':13A 'could':8A 'css':2A 'cve':14A,17A 'firefox':1A 'free':7A 'let':9A 'page':11A 'pars':3A 'run':12A 'use':5A 'use-after-fre':4A","search_b":"'attack':52B 'beyond':55B 'browser':20B 'bug':28B 'compon':36B 'comput':35B 'confirm':62B 'css':32B 'firefox':21B,30B 'free':27B 'freed':44B 'impact':59B 'let':37B 'memori':38B 'pars':33B 'reus':40B 'runtim':22B 'sourc':46B 'state':49B 'use':25B 'use-after-fre':24B","search_c":"'153.7':84C '160':80C 'compon':73C 'comput':72C 'css':69C 'esr':83C 'firefox':79C,82C 'fix':77C 'free':66C 'pars':70C 'use':64C 'use-after-fre':63C 'vulner':75C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T14:17:22+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-124889","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-124889","severity":null,"published_at":"2026-11-10T14:17:22+00:00","modified_at":"2026-11-10T14:17:22+00:00","first_seen_at":"2026-11-10T14:22:15+00:00","fetched_at":"2026-11-10T14:22:15+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"}