{"id":"CVE-2026-120789","kind":"vulnerability","aliases":["CVE-2026-120789"],"related":[],"title":"Microsoft Excel: heap overflow lets an unauthorized network attacker run code","description":"Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.","summary":"A heap-based buffer overflow in Microsoft Office Excel can be triggered over a network by an unauthenticated attacker. Successful exploitation lets the attacker execute code on the affected machine.","severity":"high","cvss":8.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["excel","microsoft-office","vendor","windows"],"not_affected_if":[],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-11-10T19:20:28+00:00","first_seen_at":"2026-11-10T19:25:08+00:00","triaged_at":"2026-11-10T19:27:51+00:00","updated_at":"2026-11-10T19:27:51+00:00","category":"vendor","confidence":0.5,"triage":{"at":"2026-11-10T19:27:51Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Microsoft Excel: heap overflow lets an unauthorized network attacker run code","impact":"high","summary":"A heap-based buffer overflow in Microsoft Office Excel can be triggered over a network by an unauthenticated attacker. Successful exploitation lets the attacker execute code on the affected machine.","audience":"everyone","category":"vendor","nicknames":[],"who_cares":["excel","microsoft-office","windows"],"confidence":0.5,"fix_status":"unknown","needs_auth":"no","worst_case":"Attacker executes code on the machine over the network","analyst_note":"Check Microsoft's security update guide for CVE-2026-120789 for affected builds, the fixed update, and whether user interaction is required.","how_to_check":"- unknown","plain_action":"Update Microsoft Excel through Microsoft Update once Microsoft publishes a fix for CVE-2026-120789.","product_name":"","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Machines running Microsoft Office Excel. The sources do not say which Excel builds or file-handling paths are affected, or whether preview or opening a file is enough to trigger it. unknown","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000678,"input_tokens":4496,"output_tokens":457,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Check Microsoft's security update guide for CVE-2026-120789 for affected builds, the fixed update, and whether user interaction is required.","search":"'-120789':14A,17A '-2026':13A,16A 'affect':53B 'allow':64C 'attack':9A,43B,48B,67C 'base':27B,57C 'buffer':28B,58C 'code':11A,50B,70C 'cve':12A,15A 'excel':2A,18B,33B,63C 'execut':49B,69C 'exploit':45B 'heap':3A,26B,56C 'heap-bas':25B,55C 'let':5A,46B 'machin':54B 'microsoft':1A,20B,31B,61C 'microsoft-offic':19B 'network':8A,39B,73C 'offic':21B,32B,62C 'overflow':4A,29B,59C 'run':10A 'success':44B 'trigger':36B 'unauthent':42B 'unauthor':7A,66C 'vendor':22B 'window':23B","nicknames":[],"mitigations":[],"who_affected":"Machines running Microsoft Office Excel. The sources do not say which Excel builds or file-handling paths are affected, or whether preview or opening a file is enough to trigger it. unknown","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"everyone","plain_action":"Update Microsoft Excel through Microsoft Update once Microsoft publishes a fix for CVE-2026-120789.","pkeys":[],"ptokens":[],"labels":["excel","high","microsoftoffice","vendor","windows"],"campaign_type":null,"search_a":"'-120789':14A,17A '-2026':13A,16A 'attack':9A 'code':11A 'cve':12A,15A 'excel':2A 'heap':3A 'let':5A 'microsoft':1A 'network':8A 'overflow':4A 'run':10A 'unauthor':7A","search_b":"'affect':53B 'attack':43B,48B 'base':27B 'buffer':28B 'code':50B 'excel':18B,33B 'execut':49B 'exploit':45B 'heap':26B 'heap-bas':25B 'let':46B 'machin':54B 'microsoft':20B,31B 'microsoft-offic':19B 'network':39B 'offic':21B,32B 'overflow':29B 'success':44B 'trigger':36B 'unauthent':42B 'vendor':22B 'window':23B","search_c":"'allow':64C 'attack':67C 'base':57C 'buffer':58C 'code':70C 'excel':63C 'execut':69C 'heap':56C 'heap-bas':55C 'microsoft':61C 'network':73C 'offic':62C 'overflow':59C 'unauthor':66C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:20:28+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-120789","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120789","severity":null,"published_at":"2026-11-10T19:20:28+00:00","modified_at":"2026-11-10T19:20:28+00:00","first_seen_at":"2026-11-10T19:25:08+00:00","fetched_at":"2026-11-10T19:25:08+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"}