{"id":"CVE-2026-117951","kind":"vulnerability","aliases":["CVE-2026-117951"],"related":[],"title":"Firefox: use-after-free in DOM core and HTML lets code run","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 can corrupt memory when a page triggers it. The sources do not say what an attacker gets beyond memory corruption, so the impact is unconfirmed.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["desktop-browsers","firefox","managed-fleets","runtime"],"not_affected_if":["no-firefox-installed"],"how_to_check":"- Open `about:support` in Firefox and read the version; unknown whether the sources list affected versions beyond the fixed ones.\n- Check the installed ESR branch version against the fixed releases listed in the fix field.","fix":"- Update Firefox to `159` or later on the current channel.\n- Update Firefox ESR to `115.44` on the 115 branch or `153.6` on the 153 branch.","status":"open","published_at":"2026-10-27T14:16:51+00:00","first_seen_at":"2026-10-27T14:32:23+00:00","triaged_at":"2026-10-27T14:35:38+00:00","updated_at":"2026-10-27T14:35:38+00:00","category":"runtime","confidence":0.4,"triage":{"at":"2026-10-27T14:35:38Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later on the current channel.\n- Update Firefox ESR to `115.44` on the 115 branch or `153.6` on the 153 branch.","reach":"internet","title":"Firefox: use-after-free in DOM core and HTML lets code run","impact":"high","summary":"A use-after-free bug in the DOM Core and HTML component of Firefox can corrupt memory when a page triggers it. The sources do not say what an attacker gets beyond memory corruption, so the impact is unconfirmed.","category":"runtime","nicknames":[],"who_cares":["firefox","desktop-browsers","managed-fleets"],"confidence":0.4,"needs_auth":"no","worst_case":"unknown; memory corruption in the browser, possibly code execution","analyst_note":"Check the Mozilla security advisory for this CVE to confirm the exploit impact, whether it is exploitable from web content, and the exact affected version ranges.","how_to_check":"- Open `about:support` in Firefox and read the version; unknown whether the sources list affected versions beyond the fixed ones.\n- Check the installed ESR branch version against the fixed releases listed in the fix field.","needs_analyst":true,"not_affected_if":["no-firefox-installed"],"who_is_affected":"Anyone running an unpatched Firefox build that renders web content, including desktop installs on managed fleets. Server-side software that does not run a browser engine is not affected by this entry. The sources do not describe a configuration that changes exposure.","user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"unknown"},"cost_usd":0.000604,"input_tokens":3254,"output_tokens":558,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117951':16A,19A '-2026':15A,18A '115.44':87C '153.6':91C '159':84C 'attack':58B 'beyond':60B 'browser':22B 'bug':33B 'code':12A 'compon':40B,77C 'core':8A,37B,75C 'corrupt':44B,62B 'cve':14A,17A 'desktop':21B 'desktop-brows':20B 'dom':7A,36B,74C 'esr':86C,90C 'firefox':1A,23B,42B,83C,85C,89C 'fix':81C 'fleet':26B 'free':5A,32B,71C 'get':59B 'html':10A,39B,76C 'impact':65B 'let':11A 'manag':25B 'managed-fleet':24B 'memori':45B,61B 'page':48B 'run':13A 'runtim':27B 'say':55B 'sourc':52B 'trigger':49B 'unconfirm':67B 'use':3A,30B,69C 'use-after-fre':2A,29B,68C 'vulner':79C","nicknames":[],"mitigations":[],"who_affected":"Anyone running an unpatched Firefox build that renders web content, including desktop installs on managed fleets. Server-side software that does not run a browser engine is not affected by this entry. The sources do not describe a configuration that changes exposure.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:51+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117951","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117951","severity":null,"published_at":"2026-10-27T14:16:51+00:00","modified_at":"2026-10-27T14:16:51+00:00","first_seen_at":"2026-10-27T14:32:23+00:00","fetched_at":"2026-10-27T14:32:23+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"}