{"id":"CVE-2026-117887","kind":"vulnerability","aliases":["CVE-2026-117887"],"related":[],"title":"Firefox: use-after-free in DOM core and HTML lets attackers 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 DOM Core and HTML component of Firefox was fixed in Firefox 159 and the ESR releases 115.44 and 153.6. Use-after-free flaws in browser engines are commonly abused to corrupt memory and may let a malicious web page execute code, but the sources do not say how it is triggered.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browsers","desktop","firefox","runtime"],"not_affected_if":[],"how_to_check":"- Run `firefox --version` (or check About Firefox) and compare against `159`, `115.44` and `153.6`.\n- Check the ESR line in use: `115.44` or `153.6` for ESR installs.","fix":"- Update Firefox to `159` or later.\n- Update Firefox ESR 115 to `115.44` or later.\n- Update Firefox ESR 153 to `153.6` or later.","status":"open","published_at":"2026-10-27T14:16:44+00:00","first_seen_at":"2026-10-27T14:32:21+00:00","triaged_at":"2026-10-27T14:37:53+00:00","updated_at":"2026-10-27T14:37:53+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-27T14:37:53Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later.\n- Update Firefox ESR 115 to `115.44` or later.\n- Update Firefox ESR 153 to `153.6` or later.","reach":"internet","title":"Firefox: use-after-free in DOM core and HTML lets attackers run code","impact":"high","summary":"A use-after-free bug in the DOM Core and HTML component of Firefox was fixed in Firefox 159 and the ESR releases 115.44 and 153.6. Use-after-free flaws in browser engines are commonly abused to corrupt memory and may let a malicious web page execute code, but the sources do not say how it is triggered.","category":"runtime","nicknames":[],"who_cares":["firefox","desktop","browsers"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown: memory corruption could allow code execution in the browser","analyst_note":"Check the Mozilla security advisory for this CVE for trigger conditions, exploitation status and whether the bug allows sandbox escape.","how_to_check":"- Run `firefox --version` (or check About Firefox) and compare against `159`, `115.44` and `153.6`.\n- Check the ESR line in use: `115.44` or `153.6` for ESR installs.","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Anyone running a Firefox build older than the fixed versions, including desktop installs and managed fleets pinned to ESR. The sources do not describe the exact page or content needed to trigger it. Systems already on the fixed versions are not affected.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000617,"input_tokens":3254,"output_tokens":584,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117887':17A,20A '-2026':16A,19A '115.44':49B,104C '153.6':51B,108C '159':44B,101C 'abus':62B 'attack':12A 'browser':21B,58B 'bug':30B 'code':14A,74B 'common':61B 'compon':37B,94C 'core':8A,34B,92C 'corrupt':64B 'cve':15A,18A 'desktop':22B 'dom':7A,33B,91C 'engin':59B 'esr':47B,103C,107C 'execut':73B 'firefox':1A,23B,39B,43B,100C,102C,106C 'fix':41B,98C 'flaw':56B 'free':5A,29B,55B,88C 'html':10A,36B,93C 'let':11A,68B 'malici':70B 'may':67B 'memori':65B 'page':72B 'releas':48B 'run':13A 'runtim':24B 'say':80B 'sourc':77B 'trigger':84B 'use':3A,27B,53B,86C 'use-after-fre':2A,26B,52B,85C 'vulner':96C 'web':71B","nicknames":[],"mitigations":[],"who_affected":"Anyone running a Firefox build older than the fixed versions, including desktop installs and managed fleets pinned to ESR. The sources do not describe the exact page or content needed to trigger it. Systems already on the fixed versions are not affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:44+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117887","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117887","severity":null,"published_at":"2026-10-27T14:16:44+00:00","modified_at":"2026-10-27T14:16:44+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"}