{"id":"CVE-2026-95951","kind":"vulnerability","aliases":["CVE-2026-95951"],"related":[],"title":"Windows Installer: heap overflow lets a local user gain higher privileges","description":"Heap-based buffer overflow in Windows Installer allows an authorized attacker to elevate privileges locally.","summary":"Windows Installer has a heap-based buffer overflow that lets an authorized local user raise their privileges. An attacker who already has a local account can use it to gain more control of the machine.","severity":"high","cvss":7.8,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"Windows Installer","fixed":["10.0.14393.9688","10.0.17763.9487","10.0.19044.7846","10.0.19045.7846","10.0.22631.7711","10.0.26100.9974","10.0.26200.9974","10.0.28000.3501","10.0.26300.9974","10.0.20348.5870","10.0.26100.33822"],"affected":"Windows 10 1607/Server 2016 < 10.0.14393.9688; 1809/Server 2019 < 10.0.17763.9487; 10 21H2 < 10.0.19044.7846; 10 22H2 < 10.0.19045.7846; 11 23H2 < 10.0.22631.7711; 11 24H2 < 10.0.26100.9974; 11 25H2 < 10.0.26200.9974; 11 26H1 < 10.0.28000.3501; 11 26H2 < 10.0.26300.9974; Server 2022 < 10.0.20348.5870; Server 2025 < 10.0.26100.33822","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["infrastructure","local-privilege-escalation","windows","windows-server"],"not_affected_if":["no-local-accounts","patched-build"],"how_to_check":"Run winver or '[System.Environment]::OSVersion.Version' and compare the build (10.0.x.y) with the fixed builds listed in the fix. Anything below the fixed build for your Windows version is exposed.","fix":"Install the November 2026 Microsoft cumulative update that brings your OS to at least: Win10 1607/Server 2016 10.0.14393.9688; 1809/Server 2019 10.0.17763.9487; Win10 21H2 10.0.19044.7846; Win10 22H2 10.0.19045.7846; Win11 23H2 10.0.22631.7711; Win11 24H2 10.0.26100.9974; Win11 25H2 10.0.26200.9974; Win11 26H1 10.0.28000.3501; Win11 26H2 10.0.26300.9974; Server 2022 10.0.20348.5870; Server 2025 10.0.26100.33822. KB numbers: check the MSRC entry.","status":"open","published_at":"2026-11-10T19:21:47+00:00","first_seen_at":"2026-11-10T19:25:24+00:00","triaged_at":"2026-11-10T19:38:08+00:00","updated_at":"2026-11-10T20:20:43+00:00","category":"infrastructure","confidence":0.7,"triage":{"at":"2026-11-10T19:38:08Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"Windows Installer: heap overflow lets a local user gain higher privileges","impact":"high","summary":"Windows Installer has a heap-based buffer overflow that lets an authorized local user raise their privileges. An attacker who already has a local account can use it to gain more control of the machine.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["windows"],"confidence":0.6,"fix_status":"unknown","needs_auth":"yes","worst_case":"local user gains elevated system privileges on Windows","analyst_note":"Confirm affected Windows builds and the Microsoft security update that fixes CVE-2026-95951 at the NVD entry.","how_to_check":"unknown","plain_action":"","product_name":"Windows Installer","needs_analyst":true,"not_affected_if":["no-local-accounts"],"who_is_affected":"Windows machines where a local user with an existing account can run Windows Installer. The sources do not name affected Windows builds or the patch level. unknown","user_interaction":"unknown","product_ecosystem":"vendor","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000655,"input_tokens":4488,"output_tokens":412,"severity_before":"high"},"analyst_status":"done","analyst_note":"Confirm affected Windows builds and the Microsoft security update that fixes CVE-2026-95951 at the NVD entry.","search":"'-2026':13A,16A '-95951':14A,17A 'account':54B 'allow':73C 'alreadi':50B 'attack':48B,76C 'author':41B,75C 'base':35B,67C 'buffer':36B,68C 'control':61B 'cve':12A,15A 'elev':78C 'escal':24B 'gain':9A,59B 'heap':3A,34B,66C 'heap-bas':33B,65C 'higher':10A 'infrastructur':20B 'instal':2A,30B,72C 'installer':19A 'let':5A,39B 'local':7A,22B,42B,53B,80C 'local-privilege-escal':21B 'machin':64B 'overflow':4A,37B,69C 'privileg':11A,23B,46B,79C 'rais':44B 'server':28B 'use':56B 'user':8A,43B 'window':1A,25B,27B,29B,71C 'windows':18A 'windows-serv':26B","nicknames":[],"mitigations":[],"who_affected":"Windows 10, Windows 11 and Windows Server 2016/2019/2022/2025 (including Server Core) below the fixed builds. An attacker needs an existing local account; this is local privilege escalation, not remote. Machines with no untrusted local users or shared logins (single-user, no remote desktop or CI runners) are lower priority, but still patch.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":["installer","windowsinstaller"],"ptokens":["installer","windows"],"labels":["high","infrastructure","localprivilegeescalation","vendor","windows","windowsserver"],"campaign_type":null,"search_a":"'-2026':13A,16A '-95951':14A,17A 'cve':12A,15A 'gain':9A 'heap':3A 'higher':10A 'instal':2A 'installer':19A 'let':5A 'local':7A 'overflow':4A 'privileg':11A 'user':8A 'window':1A 'windows':18A","search_b":"'account':54B 'alreadi':50B 'attack':48B 'author':41B 'base':35B 'buffer':36B 'control':61B 'escal':24B 'gain':59B 'heap':34B 'heap-bas':33B 'infrastructur':20B 'instal':30B 'let':39B 'local':22B,42B,53B 'local-privilege-escal':21B 'machin':64B 'overflow':37B 'privileg':23B,46B 'rais':44B 'server':28B 'use':56B 'user':43B 'window':25B,27B,29B 'windows-serv':26B","search_c":"'allow':73C 'attack':76C 'author':75C 'base':67C 'buffer':68C 'elev':78C 'heap':66C 'heap-bas':65C 'instal':72C 'local':80C 'overflow':69C 'privileg':79C 'window':71C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:21:47+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:L/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-2026-95951","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-95951","severity":null,"published_at":"2026-11-10T19:21:47+00:00","modified_at":"2026-11-10T19:21:49+00:00","first_seen_at":"2026-11-10T19:25:24+00:00","fetched_at":"2026-11-10T19:25:24+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-95951:2644","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-95951","severity":null,"published_at":"2026-11-10T20:20:43+00:00","modified_at":"2026-11-10T20:20:43+00:00","first_seen_at":"2026-11-10T20:20:43+00:00","fetched_at":"2026-11-10T20:20:43+00:00","note":"Builds read from NVD, which carries Microsoft's CNA affected list. MSRC page is JS-only and not read, so nothing is marked verified. KB numbers unknown. No exploitation or PoC seen.","cites":["https://nvd.nist.gov/vuln/detail/CVE-2026-95951"]}],"documents":[{"id":118005,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-95951","title":"NVD CVE-2026-95951 (Microsoft CNA data)","kind":"advisory","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"describes","confidence":null,"note":null}],"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"}