{"id":"CVE-2026-124187","kind":"vulnerability","aliases":["CVE-2026-124187"],"related":[],"title":"Microsoft Excel: use-after-free lets a remote attacker run code","description":"Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.","summary":"A memory-handling flaw in Microsoft Office Excel lets an attacker run code on a machine over a network. The sources report a CVSS score of 8.8 and do not say whether it is exploited in the wild.","severity":"high","cvss":8.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["microsoft-excel","microsoft-office","package","windows"],"not_affected_if":[],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-11-10T19:20:47+00:00","first_seen_at":"2026-11-10T19:25:13+00:00","triaged_at":"2026-11-10T19:26:16+00:00","updated_at":"2026-11-10T19:26:16+00:00","category":"package","confidence":0.5,"triage":{"at":"2026-11-10T19:26:16Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Microsoft Excel: use-after-free lets a remote attacker run code","impact":"high","summary":"A memory-handling flaw in Microsoft Office Excel lets an attacker run code on a machine over a network. The sources report a CVSS score of 8.8 and do not say whether it is exploited in the wild.","audience":"everyone","category":"package","nicknames":[],"who_cares":["microsoft-excel","microsoft-office","windows"],"confidence":0.5,"fix_status":"unknown","needs_auth":"no","worst_case":"Attacker runs code on the affected computer over the network","analyst_note":"Check the Microsoft Security Update Guide entry for CVE-2026-124187 for affected Office builds, the fixed build and whether user interaction (opening a file) is required.","how_to_check":"unknown","plain_action":"Update Microsoft Excel through Microsoft's usual update channel once Microsoft publishes a fix for this flaw.","product_name":"","needs_analyst":true,"not_affected_if":[],"who_is_affected":"unknown","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000655,"input_tokens":4482,"output_tokens":414,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Check the Microsoft Security Update Guide entry for CVE-2026-124187 for affected Office builds, the fixed build and whether user interaction (opening a file) is required.","search":"'-124187':15A,18A '-2026':14A,17A '8.8':54B 'allow':73C 'attack':10A,38B,76C 'code':12A,40B,79C 'cve':13A,16A 'cvss':51B 'excel':2A,21B,35B,72C 'execut':78C 'exploit':62B 'flaw':31B 'free':6A,68C 'handl':30B 'let':7A,36B 'machin':43B 'memori':29B 'memory-handl':28B 'microsoft':1A,20B,23B,33B,70C 'microsoft-excel':19B 'microsoft-offic':22B 'network':46B,82C 'offic':24B,34B,71C 'packag':25B 'remot':9A 'report':49B 'run':11A,39B 'say':58B 'score':52B 'sourc':48B 'unauthor':75C 'use':4A,66C 'use-after-fre':3A 'whether':59B 'wild':65B 'window':26B","nicknames":[],"mitigations":[],"who_affected":null,"tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"everyone","plain_action":"Update Microsoft Excel through Microsoft's usual update channel once Microsoft publishes a fix for this flaw.","pkeys":[],"ptokens":[],"labels":["high","microsoftexcel","microsoftoffice","package","windows"],"campaign_type":null,"search_a":"'-124187':15A,18A '-2026':14A,17A 'attack':10A 'code':12A 'cve':13A,16A 'excel':2A 'free':6A 'let':7A 'microsoft':1A 'remot':9A 'run':11A 'use':4A 'use-after-fre':3A","search_b":"'8.8':54B 'attack':38B 'code':40B 'cvss':51B 'excel':21B,35B 'exploit':62B 'flaw':31B 'handl':30B 'let':36B 'machin':43B 'memori':29B 'memory-handl':28B 'microsoft':20B,23B,33B 'microsoft-excel':19B 'microsoft-offic':22B 'network':46B 'offic':24B,34B 'packag':25B 'report':49B 'run':39B 'say':58B 'score':52B 'sourc':48B 'whether':59B 'wild':65B 'window':26B","search_c":"'allow':73C 'attack':76C 'code':79C 'excel':72C 'execut':78C 'free':68C 'microsoft':70C 'network':82C 'offic':71C 'unauthor':75C 'use':66C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:20:47+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-2026-124187","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-124187","severity":null,"published_at":"2026-11-10T19:20:47+00:00","modified_at":"2026-11-10T19:20:48+00:00","first_seen_at":"2026-11-10T19:25:13+00:00","fetched_at":"2026-11-10T19:25:13+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"}