{"id":"CVE-2026-105509","kind":"vulnerability","aliases":["CVE-2026-105509"],"related":[],"title":"Windows ReFS: use-after-free lets a local user gain higher privileges","description":"Use after free in Windows Resilient File System (ReFS) allows an authorized attacker to elevate privileges locally.","summary":"A memory bug in the Windows Resilient File System (ReFS) lets an attacker who already has a local account free memory and then reuse it. That lets them raise their privileges on the machine.","severity":"high","cvss":7.0,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["infrastructure","refs","windows"],"not_affected_if":["no-local-accounts","ntfs-only"],"how_to_check":"- Check the Windows build with `winver` and compare it with the patch date in Microsoft's security update guide for this CVE","fix":null,"status":"open","published_at":"2026-11-10T19:17:49+00:00","first_seen_at":"2026-11-10T19:24:17+00:00","triaged_at":"2026-11-10T19:54:15+00:00","updated_at":"2026-11-10T19:54:15+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-11-10T19:54:15Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"Windows ReFS: use-after-free lets a local user gain higher privileges","impact":"high","summary":"A memory bug in the Windows Resilient File System (ReFS) lets an attacker who already has a local account free memory and then reuse it. That lets them raise their privileges on the machine.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["windows","refs"],"confidence":0.5,"fix_status":"unknown","needs_auth":"yes","worst_case":"local user gains administrator or SYSTEM privileges on the machine","analyst_note":"Find the affected Windows builds and the Microsoft patch for CVE-2026-105509 in the MSRC security update guide; the NVD entry gives no version ranges.","how_to_check":"- Check the Windows build with `winver` and compare it with the patch date in Microsoft's security update guide for this CVE\n- unknown","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["ntfs-only","no-local-accounts"],"who_is_affected":"Only Windows machines that use the ReFS file system are in scope, and an attacker needs a valid local account on the machine first. The sources do not name the affected Windows builds or the patched update. Systems that only use NTFS are not described as affected.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000694,"input_tokens":4492,"output_tokens":489,"severity_before":"high"},"analyst_status":"queued","analyst_note":"Find the affected Windows builds and the Microsoft patch for CVE-2026-105509 in the MSRC security update guide; the NVD entry gives no version ranges.","search":"'-105509':16A,19A '-2026':15A,18A 'account':41B 'allow':66C 'alreadi':37B 'attack':35B,69C 'author':68C 'bug':25B 'cve':14A,17A 'elev':71C 'file':30B,63C 'free':6A,42B,59C 'gain':11A 'higher':12A 'infrastructur':20B 'let':7A,33B,49B 'local':9A,40B,73C 'machin':56B 'memori':24B,43B 'privileg':13A,53B,72C 'rais':51B 'ref':2A,21B,32B,65C 'resili':29B,62C 'reus':46B 'system':31B,64C 'use':4A,57C 'use-after-fre':3A 'user':10A 'window':1A,22B,28B,61C","nicknames":[],"mitigations":[],"who_affected":"Only Windows machines that use the ReFS file system are in scope, and an attacker needs a valid local account on the machine first. The sources do not name the affected Windows builds or the patched update. Systems that only use NTFS are not described as affected.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["high","infrastructure","refs","windows"],"campaign_type":null,"search_a":"'-105509':16A,19A '-2026':15A,18A 'cve':14A,17A 'free':6A 'gain':11A 'higher':12A 'let':7A 'local':9A 'privileg':13A 'ref':2A 'use':4A 'use-after-fre':3A 'user':10A 'window':1A","search_b":"'account':41B 'alreadi':37B 'attack':35B 'bug':25B 'file':30B 'free':42B 'infrastructur':20B 'let':33B,49B 'local':40B 'machin':56B 'memori':24B,43B 'privileg':53B 'rais':51B 'ref':21B,32B 'resili':29B 'reus':46B 'system':31B 'window':22B,28B","search_c":"'allow':66C 'attack':69C 'author':68C 'elev':71C 'file':63C 'free':59C 'local':73C 'privileg':72C 'ref':65C 'resili':62C 'system':64C 'use':57C 'window':61C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:17:49+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:L/AC:H/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-2026-105509","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-105509","severity":null,"published_at":"2026-11-10T19:17:49+00:00","modified_at":"2026-11-10T19:17:49+00:00","first_seen_at":"2026-11-10T19:24:17+00:00","fetched_at":"2026-11-10T19:24:17+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"}