{"id":"CVE-2026-118709","kind":"vulnerability","aliases":["CVE-2026-118709"],"related":[],"title":"Microsoft Excel: heap buffer overflow lets 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 Office Excel lets an unauthorized attacker run code over a network. The sources give no further detail on the trigger or affected versions.","severity":"high","cvss":8.8,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"Microsoft Office Excel","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["excel","microsoft-office","other","windows"],"not_affected_if":[],"how_to_check":"- Check whether Microsoft Excel is installed and which build it is, for example in Excel under File > Account > About Excel.","fix":null,"status":"open","published_at":"2026-11-10T19:19:46+00:00","first_seen_at":"2026-11-10T19:24:53+00:00","triaged_at":"2026-11-10T19:29:43+00:00","updated_at":"2026-11-10T19:29:43+00:00","category":"other","confidence":0.4,"triage":{"at":"2026-11-10T19:29:43Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Microsoft Excel: heap buffer overflow lets remote attacker run code","impact":"high","summary":"A heap-based buffer overflow in Microsoft Office Excel lets an unauthorized attacker run code over a network. The sources give no further detail on the trigger or affected versions.","audience":"businesses","category":"other","nicknames":[],"who_cares":["microsoft-office","excel","windows"],"confidence":0.4,"fix_status":"unknown","needs_auth":"no","worst_case":"Attacker runs code on the affected machine over the network.","analyst_note":"Find Microsoft's MSRC advisory for CVE-2026-118709 to confirm affected builds, the fixed update and whether user interaction (opening a file) is needed.","how_to_check":"- Check whether Microsoft Excel is installed and which build it is, for example in Excel under File > Account > About Excel.\n- unknown for the affected version range: the sources do not say.","plain_action":"","product_name":"Microsoft Office Excel","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Organizations running Microsoft Office Excel are likely exposed, since the flaw is reachable over a network without credentials according to the NVD description. The sources do not list affected builds or the trigger path, so who can skip it is unknown.","user_interaction":"unknown","product_ecosystem":"vendor","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000709,"input_tokens":4496,"output_tokens":518,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Find Microsoft's MSRC advisory for CVE-2026-118709 to confirm affected builds, the fixed update and whether user interaction (opening a file) is needed.","search":"'-118709':13A,16A '-2026':12A,15A 'affect':55B 'allow':66C 'attack':8A,39B,69C 'base':29B,59C 'buffer':4A,30B,60C 'code':10A,41B,72C 'cve':11A,14A 'detail':50B 'excel':2A,19A,20B,35B,65C 'execut':71C 'give':47B 'heap':3A,28B,58C 'heap-bas':27B,57C 'let':6A,36B 'microsoft':1A,17A,22B,33B,63C 'microsoft-offic':21B 'network':44B,75C 'offic':23B,34B,64C 'office':18A 'overflow':5A,31B,61C 'remot':7A 'run':9A,40B 'sourc':46B 'trigger':53B 'unauthor':38B,68C 'version':56B 'window':25B","nicknames":[],"mitigations":[],"who_affected":"Organizations running Microsoft Office Excel are likely exposed, since the flaw is reachable over a network without credentials according to the NVD description. The sources do not list affected builds or the trigger path, so who can skip it is unknown.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":["microsoftofficeexcel","officeexcel"],"ptokens":["excel","microsoft","office"],"labels":["excel","high","microsoftoffice","other","vendor","windows"],"campaign_type":null,"search_a":"'-118709':13A,16A '-2026':12A,15A 'attack':8A 'buffer':4A 'code':10A 'cve':11A,14A 'excel':2A,19A 'heap':3A 'let':6A 'microsoft':1A,17A 'office':18A 'overflow':5A 'remot':7A 'run':9A","search_b":"'affect':55B 'attack':39B 'base':29B 'buffer':30B 'code':41B 'detail':50B 'excel':20B,35B 'give':47B 'heap':28B 'heap-bas':27B 'let':36B 'microsoft':22B,33B 'microsoft-offic':21B 'network':44B 'offic':23B,34B 'overflow':31B 'run':40B 'sourc':46B 'trigger':53B 'unauthor':38B 'version':56B 'window':25B","search_c":"'allow':66C 'attack':69C 'base':59C 'buffer':60C 'code':72C 'excel':65C 'execut':71C 'heap':58C 'heap-bas':57C 'microsoft':63C 'network':75C 'offic':64C 'overflow':61C 'unauthor':68C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:19:46+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-2026-118709","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118709","severity":null,"published_at":"2026-11-10T19:19:46+00:00","modified_at":"2026-11-10T19:19:46+00:00","first_seen_at":"2026-11-10T19:24:53+00:00","fetched_at":"2026-11-10T19:24:53+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"}