{"id":"CVE-2026-123379","kind":"vulnerability","aliases":["CVE-2026-123379"],"related":[],"title":"Microsoft Outlook: heap buffer overflow lets a remote attacker run code","description":"Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.","summary":"A heap-based buffer overflow in Microsoft Office Outlook lets an unauthenticated attacker over a network trigger memory corruption. The sources say an attacker can execute code on the affected machine.","severity":"high","cvss":7.5,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["microsoft-office","other","outlook","windows"],"not_affected_if":[],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-11-10T19:20:41+00:00","first_seen_at":"2026-11-10T19:25:12+00:00","triaged_at":"2026-11-10T19:44:18+00:00","updated_at":"2026-11-10T19:44:18+00:00","category":"other","confidence":0.5,"triage":{"at":"2026-11-10T19:44:18Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Microsoft Outlook: heap buffer overflow lets a remote attacker run code","impact":"high","summary":"A heap-based buffer overflow in Microsoft Office Outlook lets an unauthenticated attacker over a network trigger memory corruption. The sources say an attacker can execute code on the affected machine.","audience":"everyone","category":"other","nicknames":[],"who_cares":["outlook","microsoft-office","windows"],"confidence":0.5,"fix_status":"unknown","needs_auth":"no","worst_case":"Attacker runs code on the affected machine over the network","analyst_note":"Check the Microsoft Security Response Center advisory for CVE-2026-123379 for affected versions, fixed builds and whether user interaction is required.","how_to_check":"- unknown","plain_action":"Update Microsoft Outlook to the latest version through Microsoft's normal update channel once a fix is listed for your version.","product_name":"","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Anyone running an affected version of Microsoft Office Outlook may be exposed, since the flaw is reachable over a network without credentials. The sources do not say which Outlook versions or configurations are affected, or whether user interaction is needed.","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000688,"input_tokens":4498,"output_tokens":477,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Check the Microsoft Security Response Center advisory for CVE-2026-123379 for affected versions, fixed builds and whether user interaction is required.","search":"'-123379':14A,17A '-2026':13A,16A 'affect':54B 'allow':65C 'attack':9A,37B,48B,68C 'base':27B,58C 'buffer':4A,28B,59C 'code':11A,51B,71C 'corrupt':43B 'cve':12A,15A 'execut':50B,70C 'heap':3A,26B,57C 'heap-bas':25B,56C 'let':6A,34B 'machin':55B 'memori':42B 'microsoft':1A,19B,31B,62C 'microsoft-offic':18B 'network':40B,74C 'offic':20B,32B,63C 'outlook':2A,22B,33B,64C 'overflow':5A,29B,60C 'remot':8A 'run':10A 'say':46B 'sourc':45B 'trigger':41B 'unauthent':36B 'unauthor':67C 'window':23B","nicknames":[],"mitigations":[],"who_affected":"Anyone running an affected version of Microsoft Office Outlook may be exposed, since the flaw is reachable over a network without credentials. The sources do not say which Outlook versions or configurations are affected, or whether user interaction is needed.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"everyone","plain_action":"Update Microsoft Outlook to the latest version through Microsoft's normal update channel once a fix is listed for your version.","pkeys":[],"ptokens":[],"labels":["high","microsoftoffice","other","outlook","windows"],"campaign_type":null,"search_a":"'-123379':14A,17A '-2026':13A,16A 'attack':9A 'buffer':4A 'code':11A 'cve':12A,15A 'heap':3A 'let':6A 'microsoft':1A 'outlook':2A 'overflow':5A 'remot':8A 'run':10A","search_b":"'affect':54B 'attack':37B,48B 'base':27B 'buffer':28B 'code':51B 'corrupt':43B 'execut':50B 'heap':26B 'heap-bas':25B 'let':34B 'machin':55B 'memori':42B 'microsoft':19B,31B 'microsoft-offic':18B 'network':40B 'offic':20B,32B 'outlook':22B,33B 'overflow':29B 'say':46B 'sourc':45B 'trigger':41B 'unauthent':36B 'window':23B","search_c":"'allow':65C 'attack':68C 'base':58C 'buffer':59C 'code':71C 'execut':70C 'heap':57C 'heap-bas':56C 'microsoft':62C 'network':74C 'offic':63C 'outlook':64C 'overflow':60C 'unauthor':67C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:20:41+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/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-2026-123379","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123379","severity":null,"published_at":"2026-11-10T19:20:41+00:00","modified_at":"2026-11-10T19:20:41+00:00","first_seen_at":"2026-11-10T19:25:12+00:00","fetched_at":"2026-11-10T19:25:12+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"}