{"id":"CVE-2026-119816","kind":"vulnerability","aliases":["CVE-2026-119816"],"related":[],"title":"Windows: Microsoft Account Sign-in Assistant heap overflow allows local privilege escalation","description":"Heap-based buffer overflow in Windows Microsoft Account Sign-in Assistant allows an authorized attacker to elevate privileges locally.","summary":"A heap-based buffer overflow in the Windows Microsoft Account Sign-in Assistant service lets an authorized local user raise their privileges. The sources do not give the affected Windows versions or a fixed build.","severity":"high","cvss":7.8,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"Microsoft Account Sign-in Assistant","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["infrastructure","microsoft-account","windows"],"not_affected_if":["no-local-untrusted-users"],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-11-10T19:19:56+00:00","first_seen_at":"2026-11-10T19:24:57+00:00","triaged_at":"2026-11-10T19:40:30+00:00","updated_at":"2026-11-10T19:40:30+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-11-10T19:40:30Z","model":"claude-haiku-5-5","output":{"fix":"- unknown","reach":"local","title":"Windows: Microsoft Account Sign-in Assistant heap overflow allows local privilege escalation","impact":"high","summary":"A heap-based buffer overflow in the Windows Microsoft Account Sign-in Assistant service lets an authorized local user raise their privileges. The sources do not give the affected Windows versions or a fixed build.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["windows","microsoft-account"],"confidence":0.6,"fix_status":"unknown","needs_auth":"yes","worst_case":"local user gains higher privileges, possibly full system control","analyst_note":"Find the affected Windows builds and the Microsoft security update that fixes CVE-2026-119816 in the MSRC advisory.","how_to_check":"- unknown","plain_action":"","product_name":"Microsoft Account Sign-in Assistant","needs_analyst":true,"not_affected_if":["no-local-untrusted-users"],"who_is_affected":"Machines running Windows with the Microsoft Account Sign-in Assistant service present. An attacker needs a local account on the machine first. The sources do not list affected versions.","user_interaction":"unknown","product_ecosystem":"vendor","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000684,"input_tokens":4510,"output_tokens":467,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Find the affected Windows builds and the Microsoft security update that fixes CVE-2026-119816 in the MSRC advisory.","search":"'-119816':16A,19A '-2026':15A,18A 'account':3A,21A,29B,41B,76C 'affect':61B 'allow':10A,81C 'assist':7A,45B,80C 'assistant':25A 'attack':84C 'author':49B,83C 'base':34B,70C 'buffer':35B,71C 'build':67B 'cve':14A,17A 'elev':86C 'escal':13A 'fix':66B 'give':59B 'heap':8A,33B,69C 'heap-bas':32B,68C 'in':24A 'infrastructur':26B 'let':47B 'local':11A,50B,88C 'microsoft':2A,20A,28B,40B,75C 'microsoft-account':27B 'overflow':9A,36B,72C 'privileg':12A,54B,87C 'rais':52B 'servic':46B 'sign':5A,23A,43B,78C 'sign-in':4A,22A,42B,77C 'sourc':56B 'user':51B 'version':63B 'window':1A,30B,39B,62B,74C","nicknames":[],"mitigations":[],"who_affected":"Machines running Windows with the Microsoft Account Sign-in Assistant service present. An attacker needs a local account on the machine first. The sources do not list affected versions.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":["accountsigninassistant","microsoftaccountsigninassistant"],"ptokens":["account","assistant","in","microsoft","sign"],"labels":["high","infrastructure","microsoftaccount","vendor","windows"],"campaign_type":null,"search_a":"'-119816':16A,19A '-2026':15A,18A 'account':3A,21A 'allow':10A 'assist':7A 'assistant':25A 'cve':14A,17A 'escal':13A 'heap':8A 'in':24A 'local':11A 'microsoft':2A,20A 'overflow':9A 'privileg':12A 'sign':5A,23A 'sign-in':4A,22A 'window':1A","search_b":"'account':29B,41B 'affect':61B 'assist':45B 'author':49B 'base':34B 'buffer':35B 'build':67B 'fix':66B 'give':59B 'heap':33B 'heap-bas':32B 'infrastructur':26B 'let':47B 'local':50B 'microsoft':28B,40B 'microsoft-account':27B 'overflow':36B 'privileg':54B 'rais':52B 'servic':46B 'sign':43B 'sign-in':42B 'sourc':56B 'user':51B 'version':63B 'window':30B,39B,62B","search_c":"'account':76C 'allow':81C 'assist':80C 'attack':84C 'author':83C 'base':70C 'buffer':71C 'elev':86C 'heap':69C 'heap-bas':68C 'local':88C 'microsoft':75C 'overflow':72C 'privileg':87C 'sign':78C 'sign-in':77C 'window':74C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:19:56+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-119816","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119816","severity":null,"published_at":"2026-11-10T19:19:56+00:00","modified_at":"2026-11-10T19:19:56+00:00","first_seen_at":"2026-11-10T19:24:57+00:00","fetched_at":"2026-11-10T19:24:57+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"}