{"id":"CVE-2026-117869","kind":"vulnerability","aliases":["CVE-2026-117869"],"related":[],"title":"Firefox: use-after-free in DOM core and HTML lets a page 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 lets memory be reused after it is freed. The sources do not say what an attacker can get beyond that; Mozilla fixed it in Firefox 159, ESR 115.44 and ESR 153.6.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browser","desktop","firefox","package"],"not_affected_if":["already-on-fixed-version"],"how_to_check":"- Run `firefox --version` or open the About Firefox page and compare against `159`, `115.44` or `153.6`\n- On managed fleets, check the installed Firefox ESR version against `115.44` or `153.6`","fix":"- Update Firefox to `159` or later\n- Update Firefox ESR to `115.44` or `153.6`","status":"open","published_at":"2026-10-27T14:16:41+00:00","first_seen_at":"2026-10-27T14:32:21+00:00","triaged_at":"2026-10-27T14:39:15+00:00","updated_at":"2026-10-27T14:39:15+00:00","category":"package","confidence":0.5,"triage":{"at":"2026-10-27T14:39:15Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later\n- Update Firefox ESR to `115.44` or `153.6`","reach":"unknown","title":"Firefox: use-after-free in DOM core and HTML lets a page run code","impact":"high","summary":"A use-after-free bug in the Firefox DOM Core and HTML component lets memory be reused after it is freed. The sources do not say what an attacker can get beyond that; Mozilla fixed it in Firefox 159, ESR 115.44 and ESR 153.6.","category":"package","nicknames":[],"who_cares":["firefox","desktop","browser"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown; memory corruption in browser DOM code","analyst_note":"Check the Mozilla security advisory for this CVE to confirm trigger conditions and whether it is exploitable from web content.","how_to_check":"- Run `firefox --version` or open the About Firefox page and compare against `159`, `115.44` or `153.6`\n- On managed fleets, check the installed Firefox ESR version against `115.44` or `153.6`","needs_analyst":true,"not_affected_if":["already-on-fixed-version"],"who_is_affected":"Anyone running Firefox or Firefox ESR builds older than the fixed versions, including desktop users and managed fleets that pin ESR. The sources do not say whether a specific configuration or site is needed to trigger it, so unknown.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000595,"input_tokens":3254,"output_tokens":539,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117869':18A,21A '-2026':17A,20A '115.44':67B,90C '153.6':70B,94C '159':65B,87C 'attack':55B 'beyond':58B 'browser':22B 'bug':31B 'code':15A 'compon':39B,80C 'core':8A,36B,78C 'cve':16A,19A 'desktop':23B 'dom':7A,35B,77C 'esr':66B,69B,89C,93C 'firefox':1A,24B,34B,64B,86C,88C,92C 'fix':61B,84C 'free':5A,30B,74C 'freed':47B 'get':57B 'html':10A,38B,79C 'let':11A,40B 'memori':41B 'mozilla':60B 'packag':25B 'page':13A 'reus':43B 'run':14A 'say':52B 'sourc':49B 'use':3A,28B,72C 'use-after-fre':2A,27B,71C 'vulner':82C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox or Firefox ESR builds older than the fixed versions, including desktop users and managed fleets that pin ESR. The sources do not say whether a specific configuration or site is needed to trigger it, so unknown.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:41+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117869","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117869","severity":null,"published_at":"2026-10-27T14:16:41+00:00","modified_at":"2026-10-27T14:16:41+00:00","first_seen_at":"2026-10-27T14:32:21+00:00","fetched_at":"2026-10-27T14:32:21+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"}