{"id":"CVE-2026-118739","kind":"vulnerability","aliases":["CVE-2026-118739"],"related":[],"title":"Windows DHCP Client: memory leak lets nearby attacker deny service","description":"Missing release of memory after effective lifetime in Windows DHCP Client allows an unauthorized attacker to deny service over an adjacent network.","summary":"The Windows DHCP Client does not release memory after it is no longer needed, a memory leak. An unauthorized attacker on the same adjacent network can exhaust memory and deny service to the machine.","severity":"medium","cvss":6.5,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["dhcp-client","enterprise-endpoints","infrastructure","windows"],"not_affected_if":["no-adjacent-attacker","static-addressing"],"how_to_check":"- Check the Windows build with `winver` and compare it against the Microsoft security update guide entry for CVE-2026-118739","fix":null,"status":"open","published_at":"2026-11-10T19:19:50+00:00","first_seen_at":"2026-11-10T19:24:55+00:00","triaged_at":"2026-11-10T19:57:42+00:00","updated_at":"2026-11-10T19:57:42+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-11-10T19:57:42Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Windows DHCP Client: memory leak lets nearby attacker deny service","impact":"low","summary":"The Windows DHCP Client does not release memory after it is no longer needed, a memory leak. An unauthorized attacker on the same adjacent network can exhaust memory and deny service to the machine.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["windows","dhcp-client","enterprise-endpoints"],"confidence":0.5,"fix_status":"unknown","needs_auth":"yes","worst_case":"Denial of service on the machine through memory exhaustion","analyst_note":"Confirm affected Windows builds and the fixed update from the Microsoft Security Update Guide entry for CVE-2026-118739.","how_to_check":"- Check the Windows build with `winver` and compare it against the Microsoft security update guide entry for CVE-2026-118739\n- unknown for other checks; the sources do not say","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["static-addressing","no-adjacent-attacker"],"who_is_affected":"Windows machines that use DHCP to get network addresses are the ones with the DHCP Client service running. Exposure requires an attacker on the same adjacent network segment. Hosts with static addressing and no DHCP client use are less exposed. The sources do not give affected builds.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.00071,"input_tokens":4502,"output_tokens":519,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-118739':13A,16A '-2026':12A,15A 'adjac':48B,79C 'allow':70C 'attack':8A,44B,73C 'client':3A,19B,28B,69C 'cve':11A,14A 'deni':9A,54B,75C 'dhcp':2A,18B,27B,68C 'dhcp-client':17B 'effect':64C 'endpoint':22B 'enterpris':21B 'enterprise-endpoint':20B 'exhaust':51B 'infrastructur':23B 'leak':5A,41B 'let':6A 'lifetim':65C 'longer':37B 'machin':58B 'memori':4A,32B,40B,52B,62C 'miss':59C 'nearbi':7A 'need':38B 'network':49B,80C 'releas':31B,60C 'servic':10A,55B,76C 'unauthor':43B,72C 'window':1A,24B,26B,67C","nicknames":[],"mitigations":[],"who_affected":"Windows machines that use DHCP to get network addresses are the ones with the DHCP Client service running. Exposure requires an attacker on the same adjacent network segment. Hosts with static addressing and no DHCP client use are less exposed. The sources do not give affected builds.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["dhcpclient","enterpriseendpoints","infrastructure","medium","windows"],"campaign_type":null,"search_a":"'-118739':13A,16A '-2026':12A,15A 'attack':8A 'client':3A 'cve':11A,14A 'deni':9A 'dhcp':2A 'leak':5A 'let':6A 'memori':4A 'nearbi':7A 'servic':10A 'window':1A","search_b":"'adjac':48B 'attack':44B 'client':19B,28B 'deni':54B 'dhcp':18B,27B 'dhcp-client':17B 'endpoint':22B 'enterpris':21B 'enterprise-endpoint':20B 'exhaust':51B 'infrastructur':23B 'leak':41B 'longer':37B 'machin':58B 'memori':32B,40B,52B 'need':38B 'network':49B 'releas':31B 'servic':55B 'unauthor':43B 'window':24B,26B","search_c":"'adjac':79C 'allow':70C 'attack':73C 'client':69C 'deni':75C 'dhcp':68C 'effect':64C 'lifetim':65C 'memori':62C 'miss':59C 'network':80C 'releas':60C 'servic':76C 'unauthor':72C 'window':67C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:19:50+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-118739","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118739","severity":null,"published_at":"2026-11-10T19:19:50+00:00","modified_at":"2026-11-10T19:19:50+00:00","first_seen_at":"2026-11-10T19:24:55+00:00","fetched_at":"2026-11-10T19:24:55+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"}