{"id":"CVE-2026-118720","kind":"vulnerability","aliases":["CVE-2026-118720"],"related":[],"title":"Microsoft Excel: stack buffer overflow lets a remote attacker run code","description":"Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.","summary":"A stack-based buffer overflow in Microsoft Office Excel lets an unauthorized attacker run code over a network. The sources do not describe the trigger file or user action beyond that.","severity":"high","cvss":8.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["excel","microsoft-office","package","windows"],"not_affected_if":[],"how_to_check":"- Check the installed Excel build against Microsoft's security update guide for CVE-2026-118720.","fix":null,"status":"open","published_at":"2026-11-10T19:19:47+00:00","first_seen_at":"2026-11-10T19:24:54+00:00","triaged_at":"2026-11-10T19:28:19+00:00","updated_at":"2026-11-10T19:28:19+00:00","category":"package","confidence":0.5,"triage":{"at":"2026-11-10T19:28:19Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Microsoft Excel: stack buffer overflow lets a remote attacker run code","impact":"high","summary":"A stack-based buffer overflow in Microsoft Office Excel lets an unauthorized attacker run code over a network. The sources do not describe the trigger file or user action beyond that.","audience":"everyone","category":"package","nicknames":[],"who_cares":["excel","microsoft-office","windows"],"confidence":0.5,"fix_status":"unknown","needs_auth":"no","worst_case":"Attacker runs code on the victim's machine over the network","analyst_note":"Check Microsoft's security update guide for CVE-2026-118720 for affected builds, fixed versions, and whether user interaction is needed.","how_to_check":"- Check the installed Excel build against Microsoft's security update guide for CVE-2026-118720.\n- unknown","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Organizations and people running Microsoft Office Excel. The sources do not say which Excel builds or configurations are affected, or whether opening a file is required.","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000667,"input_tokens":4496,"output_tokens":435,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Check Microsoft's security update guide for CVE-2026-118720 for affected builds, fixed versions, and whether user interaction is needed.","search":"'-118720':14A,17A '-2026':13A,16A 'action':53B 'allow':64C 'attack':9A,37B,67C 'base':27B,57C 'beyond':54B 'buffer':4A,28B,58C 'code':11A,39B,70C 'cve':12A,15A 'describ':47B 'excel':2A,18B,33B,63C 'execut':69C 'file':50B 'let':6A,34B 'microsoft':1A,20B,31B,61C 'microsoft-offic':19B 'network':42B,73C 'offic':21B,32B,62C 'overflow':5A,29B,59C 'packag':22B 'remot':8A 'run':10A,38B 'sourc':44B 'stack':3A,26B,56C 'stack-bas':25B,55C 'trigger':49B 'unauthor':36B,66C 'user':52B 'window':23B","nicknames":[],"mitigations":[],"who_affected":"Organizations and people running Microsoft Office Excel. The sources do not say which Excel builds or configurations are affected, or whether opening a file is required.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"everyone","plain_action":null,"pkeys":[],"ptokens":[],"labels":["excel","high","microsoftoffice","package","windows"],"campaign_type":null,"search_a":"'-118720':14A,17A '-2026':13A,16A 'attack':9A 'buffer':4A 'code':11A 'cve':12A,15A 'excel':2A 'let':6A 'microsoft':1A 'overflow':5A 'remot':8A 'run':10A 'stack':3A","search_b":"'action':53B 'attack':37B 'base':27B 'beyond':54B 'buffer':28B 'code':39B 'describ':47B 'excel':18B,33B 'file':50B 'let':34B 'microsoft':20B,31B 'microsoft-offic':19B 'network':42B 'offic':21B,32B 'overflow':29B 'packag':22B 'run':38B 'sourc':44B 'stack':26B 'stack-bas':25B 'trigger':49B 'unauthor':36B 'user':52B 'window':23B","search_c":"'allow':64C 'attack':67C 'base':57C 'buffer':58C 'code':70C 'excel':63C 'execut':69C 'microsoft':61C 'network':73C 'offic':62C 'overflow':59C 'stack':56C 'stack-bas':55C 'unauthor':66C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:19:47+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-2026-118720","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118720","severity":null,"published_at":"2026-11-10T19:19:47+00:00","modified_at":"2026-11-10T19:19:48+00:00","first_seen_at":"2026-11-10T19:24:54+00:00","fetched_at":"2026-11-10T19:24:54+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"}