{"id":"CVE-2026-118302","kind":"vulnerability","aliases":["CVE-2026-118302"],"related":[],"title":"Microsoft Excel: heap buffer overflow lets a remote 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 Excel lets an unauthorized attacker run code over a network. The sources give no further detail on which file or action triggers it.","severity":"high","cvss":8.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["excel","microsoft-office","other","windows"],"not_affected_if":[],"how_to_check":"- Check the installed Excel build against Microsoft's update history for this CVE, which the sources do not list.","fix":null,"status":"open","published_at":"2026-11-10T19:19:43+00:00","first_seen_at":"2026-11-10T19:24:52+00:00","triaged_at":"2026-11-10T19:29:51+00:00","updated_at":"2026-11-10T19:29:51+00:00","category":"other","confidence":0.5,"triage":{"at":"2026-11-10T19:29:51Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Microsoft Excel: heap buffer overflow lets a remote attacker run code","impact":"high","summary":"A heap-based buffer overflow in Microsoft Excel lets an unauthorized attacker run code over a network. The sources give no further detail on which file or action triggers it.","audience":"businesses","category":"other","nicknames":[],"who_cares":["excel","microsoft-office","windows"],"confidence":0.5,"fix_status":"unknown","needs_auth":"unknown","worst_case":"Attacker runs code on the victim's machine over the network.","analyst_note":"Find the Microsoft Security Response Center advisory for CVE-2026-118302 to confirm affected Excel builds, the fixed update, and whether user interaction (opening a file) is needed.","how_to_check":"- Check the installed Excel build against Microsoft's update history for this CVE, which the sources do not list.\n- unknown","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Organisations running Microsoft Office Excel are exposed, since the flaw is in the Excel product itself. The sources do not say which Excel builds or file-handling paths are affected, so the exact exposure is unknown.","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000686,"input_tokens":4496,"output_tokens":472,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Find the Microsoft Security Response Center advisory for CVE-2026-118302 to confirm affected Excel builds, the fixed update, and whether user interaction (opening a file) is needed.","search":"'-118302':14A,17A '-2026':13A,16A 'action':52B 'allow':63C 'attack':9A,36B,66C 'base':27B,56C 'buffer':4A,28B,57C 'code':11A,38B,69C 'cve':12A,15A 'detail':47B 'excel':2A,18B,32B,62C 'execut':68C 'file':50B 'give':44B 'heap':3A,26B,55C 'heap-bas':25B,54C 'let':6A,33B 'microsoft':1A,20B,31B,60C 'microsoft-offic':19B 'network':41B,72C 'offic':21B,61C 'overflow':5A,29B,58C 'remot':8A 'run':10A,37B 'sourc':43B 'trigger':53B 'unauthor':35B,65C 'window':23B","nicknames":[],"mitigations":[],"who_affected":"Organisations running Microsoft Office Excel are exposed, since the flaw is in the Excel product itself. The sources do not say which Excel builds or file-handling paths are affected, so the exact exposure is unknown.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["excel","high","microsoftoffice","other","windows"],"campaign_type":null,"search_a":"'-118302':14A,17A '-2026':13A,16A 'attack':9A 'buffer':4A 'code':11A 'cve':12A,15A 'excel':2A 'heap':3A 'let':6A 'microsoft':1A 'overflow':5A 'remot':8A 'run':10A","search_b":"'action':52B 'attack':36B 'base':27B 'buffer':28B 'code':38B 'detail':47B 'excel':18B,32B 'file':50B 'give':44B 'heap':26B 'heap-bas':25B 'let':33B 'microsoft':20B,31B 'microsoft-offic':19B 'network':41B 'offic':21B 'overflow':29B 'run':37B 'sourc':43B 'trigger':53B 'unauthor':35B 'window':23B","search_c":"'allow':63C 'attack':66C 'base':56C 'buffer':57C 'code':69C 'excel':62C 'execut':68C 'heap':55C 'heap-bas':54C 'microsoft':60C 'network':72C 'offic':61C 'overflow':58C 'unauthor':65C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:19:43+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-2026-118302","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118302","severity":null,"published_at":"2026-11-10T19:19:43+00:00","modified_at":"2026-11-10T19:19:44+00:00","first_seen_at":"2026-11-10T19:24:52+00:00","fetched_at":"2026-11-10T19:24:52+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"}