{"id":"CVE-2026-88240","kind":"vulnerability","aliases":["CVE-2026-88240"],"related":[],"title":"Windows DHCP Client: heap overflow lets a network user gain higher privileges","description":"Heap-based buffer overflow in Windows DHCP Client allows an authorized attacker to elevate privileges over an adjacent network.","summary":"A heap-based buffer overflow in the Windows DHCP Client lets an attacker who already has authorized access and is on the adjacent network raise their privileges. The sources do not describe a remote code path from the open internet.","severity":"high","cvss":8.0,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"Windows DHCP Client","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["dhcp","infrastructure","windows"],"not_affected_if":[],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-11-10T19:21:33+00:00","first_seen_at":"2026-11-10T19:25:20+00:00","triaged_at":"2026-11-10T19:36:02+00:00","updated_at":"2026-11-10T19:36:02+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-11-10T19:36:02Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Windows DHCP Client: heap overflow lets a network user gain higher privileges","impact":"high","summary":"A heap-based buffer overflow in the Windows DHCP Client lets an attacker who already has authorized access and is on the adjacent network raise their privileges. The sources do not describe a remote code path from the open internet.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["windows","dhcp"],"confidence":0.5,"fix_status":"unknown","needs_auth":"yes","worst_case":"attacker gains elevated privileges on the Windows machine","analyst_note":"Check the Microsoft Security Update Guide entry for CVE-2026-88240 to confirm affected Windows builds, the fixed update, and whether the flaw is reachable beyond the adjacent network.","how_to_check":"- unknown","plain_action":"","product_name":"Windows DHCP Client","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Windows machines that use DHCP to get network settings are the systems to look at, since the client is the flawed component. The sources do not say which Windows builds are affected, and they do not say whether machines with static addressing are safe. unknown","user_interaction":"unknown","product_ecosystem":"vendor","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000691,"input_tokens":4500,"output_tokens":482,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Check the Microsoft Security Update Guide entry for CVE-2026-88240 to confirm affected Windows builds, the fixed update, and whether the flaw is reachable beyond the adjacent network.","search":"'-2026':14A,17A '-88240':15A,18A 'access':43B 'adjac':48B,84C 'allow':75C 'alreadi':40B 'attack':38B,78C 'author':42B,77C 'base':28B,68C 'buffer':29B,69C 'client':3A,21A,35B,74C 'code':60B 'cve':13A,16A 'describ':57B 'dhcp':2A,20A,22B,34B,73C 'elev':80C 'gain':10A 'heap':4A,27B,67C 'heap-bas':26B,66C 'higher':11A 'infrastructur':23B 'internet':65B 'let':6A,36B 'network':8A,49B,85C 'open':64B 'overflow':5A,30B,70C 'path':61B 'privileg':12A,52B,81C 'rais':50B 'remot':59B 'sourc':54B 'user':9A 'window':1A,24B,33B,72C 'windows':19A","nicknames":[],"mitigations":[],"who_affected":"Windows machines that use DHCP to get network settings are the systems to look at, since the client is the flawed component. The sources do not say which Windows builds are affected, and they do not say whether machines with static addressing are safe. unknown","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":["dhcpclient","windowsdhcpclient"],"ptokens":["client","dhcp","windows"],"labels":["dhcp","high","infrastructure","vendor","windows"],"campaign_type":null,"search_a":"'-2026':14A,17A '-88240':15A,18A 'client':3A,21A 'cve':13A,16A 'dhcp':2A,20A 'gain':10A 'heap':4A 'higher':11A 'let':6A 'network':8A 'overflow':5A 'privileg':12A 'user':9A 'window':1A 'windows':19A","search_b":"'access':43B 'adjac':48B 'alreadi':40B 'attack':38B 'author':42B 'base':28B 'buffer':29B 'client':35B 'code':60B 'describ':57B 'dhcp':22B,34B 'heap':27B 'heap-bas':26B 'infrastructur':23B 'internet':65B 'let':36B 'network':49B 'open':64B 'overflow':30B 'path':61B 'privileg':52B 'rais':50B 'remot':59B 'sourc':54B 'window':24B,33B","search_c":"'adjac':84C 'allow':75C 'attack':78C 'author':77C 'base':68C 'buffer':69C 'client':74C 'dhcp':73C 'elev':80C 'heap':67C 'heap-bas':66C 'network':85C 'overflow':70C 'privileg':81C 'window':72C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:21:33+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-88240","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-88240","severity":null,"published_at":"2026-11-10T19:21:33+00:00","modified_at":"2026-11-10T19:21:33+00:00","first_seen_at":"2026-11-10T19:25:20+00:00","fetched_at":"2026-11-10T19:25:20+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"}