{"id":"CVE-2026-117973","kind":"vulnerability","aliases":["CVE-2026-117973"],"related":[],"title":"Firefox: use-after-free in DNS networking lets attackers run code","description":"Use-after-free in the Networking: DNS component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.","summary":"A use-after-free flaw in Firefox's DNS networking component lets memory be reused after it is freed. The sources do not say what an attacker can do beyond that, so the reach and the impact are not confirmed.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browser","desktop","firefox","runtime"],"not_affected_if":["already-patched"],"how_to_check":"- Run `firefox --version` or check Help > About Firefox and compare with `159` or `153.6`\n- For ESR installs, check that the version is at least `153.6`","fix":"- Update Firefox to `159` or later\n- Update Firefox ESR to `153.6` or later","status":"open","published_at":"2026-10-27T14:16:55+00:00","first_seen_at":"2026-10-27T14:32:24+00:00","triaged_at":"2026-10-27T14:35:15+00:00","updated_at":"2026-10-27T14:35:15+00:00","category":"runtime","confidence":0.4,"triage":{"at":"2026-10-27T14:35:15Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later\n- Update Firefox ESR to `153.6` or later","reach":"unknown","title":"Firefox: use-after-free in DNS networking lets attackers run code","impact":"high","summary":"A use-after-free flaw in Firefox's DNS networking component lets memory be reused after it is freed. The sources do not say what an attacker can do beyond that, so the reach and the impact are not confirmed.","category":"runtime","nicknames":[],"who_cares":["firefox","desktop","browser"],"confidence":0.4,"needs_auth":"unknown","worst_case":"unknown; memory corruption in the browser network stack","analyst_note":"Check the Mozilla security advisory for this CVE to confirm the trigger, whether it is exploitable from web content, and the exact fixed versions.","how_to_check":"- Run `firefox --version` or check Help > About Firefox and compare with `159` or `153.6`\n- For ESR installs, check that the version is at least `153.6`","needs_analyst":true,"not_affected_if":["already-patched"],"who_is_affected":"Anyone running Firefox or Firefox ESR older than the fixed versions on desktop or managed machines. Installs already on `159` or `153.6` or later are not affected by this flaw. The sources do not say whether the bug needs a specific setting or a crafted page to trigger.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.00058,"input_tokens":3236,"output_tokens":513,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117973':15A,18A '-2026':14A,17A '153.6':83C '159':79C 'attack':10A,50B 'beyond':53B 'browser':19B 'code':12A 'compon':34B,72C 'confirm':63B 'cve':13A,16A 'desktop':20B 'dns':7A,32B,71C 'esr':82C 'firefox':1A,21B,30B,78C,81C 'fix':76C 'flaw':28B 'free':5A,27B,67C 'freed':42B 'impact':60B 'let':9A,35B 'memori':36B 'network':8A,33B,70C 'reach':57B 'reus':38B 'run':11A 'runtim':22B 'say':47B 'sourc':44B 'use':3A,25B,65C 'use-after-fre':2A,24B,64C 'vulner':74C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox or Firefox ESR older than the fixed versions on desktop or managed machines. Installs already on `159` or `153.6` or later are not affected by this flaw. The sources do not say whether the bug needs a specific setting or a crafted page to trigger.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:55+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117973","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117973","severity":null,"published_at":"2026-10-27T14:16:55+00:00","modified_at":"2026-10-27T14:16:55+00:00","first_seen_at":"2026-10-27T14:32:24+00:00","fetched_at":"2026-10-27T14:32:24+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"}