{"id":"CVE-2026-95979","kind":"vulnerability","aliases":["CVE-2026-95979"],"related":[],"title":"Windows: use-after-free in file brokering lets a local user gain privileges","description":"Use after free in Windows Brokering File System allows an authorized attacker to elevate privileges locally.","summary":"A use-after-free in the Windows Brokering File System (bfs.sys) lets a locally authenticated user gain higher privileges. Microsoft lists it in the November 2026 security updates, released 2026-11-10. I could not read the affected builds or KB numbers from MSRC. No exploitation or public PoC found.","severity":"high","cvss":7.0,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["bfs.sys","infrastructure","local-privilege-escalation","windows"],"not_affected_if":[],"how_to_check":"Check that the November 2026 cumulative update is installed (Settings > Windows Update > Update history, or PowerShell Get-HotFix). Match the KB to the one listed for your Windows version in the MSRC Update Guide entry for CVE-2026-95979.","fix":"Install the November 2026 (2026-11-10) Windows cumulative security update. The exact KB and build numbers are unknown; see the MSRC Update Guide entry for CVE-2026-95979.","status":"open","published_at":"2026-11-10T19:21:54+00:00","first_seen_at":"2026-11-10T19:25:26+00:00","triaged_at":"2026-11-10T19:49:39+00:00","updated_at":"2026-11-10T20:15:47+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-11-10T19:49:39Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"Windows: use-after-free in file brokering lets a local user gain privileges","impact":"high","summary":"A use-after-free bug in the Windows Brokering File System lets an attacker who already has a local account raise their privileges. The sources describe local privilege escalation only and give no further detail.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["windows"],"confidence":0.5,"fix_status":"unknown","needs_auth":"yes","worst_case":"local attacker gains elevated system privileges on the machine","analyst_note":"Find the affected Windows builds and Microsoft's patch date for CVE-2026-95979 in the MSRC advisory; the NVD entry has no product data.","how_to_check":"- unknown","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Windows machines where a user has a local account. The sources do not name affected Windows builds, so the exposed range is unknown. Systems where only trusted administrators log on carry less practical risk.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000651,"input_tokens":4480,"output_tokens":405,"severity_before":"high"},"analyst_status":"done","analyst_note":"Find the affected Windows builds and Microsoft's patch date for CVE-2026-95979 in the MSRC advisory; the NVD entry has no product data.","search":"'-10':60B '-11':59B '-2026':16A,19A '-95979':17A,20A '2026':54B,58B 'affect':66B 'allow':87C 'attack':90C 'authent':43B 'author':89C 'bfs.sys':21B,39B 'broker':8A,36B,84C 'build':67B 'could':62B 'cve':15A,18A 'elev':92C 'escal':26B 'exploit':74B 'file':7A,37B,85C 'found':78B 'free':5A,32B,81C 'gain':13A,45B 'higher':46B 'infrastructur':22B 'kb':69B 'let':9A,40B 'list':49B 'local':11A,24B,42B,94C 'local-privilege-escal':23B 'microsoft':48B 'msrc':72B 'novemb':53B 'number':70B 'poc':77B 'privileg':14A,25B,47B,93C 'public':76B 'read':64B 'releas':57B 'secur':55B 'system':38B,86C 'updat':56B 'use':3A,30B,79C 'use-after-fre':2A,29B 'user':12A,44B 'window':1A,27B,35B,83C","nicknames":[],"mitigations":[],"who_affected":"Windows machines where a user has a local account. The sources do not name affected Windows builds, so the exposed range is unknown. Systems where only trusted administrators log on carry less practical risk.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["bfssys","high","infrastructure","localprivilegeescalation","windows"],"campaign_type":null,"search_a":"'-2026':16A,19A '-95979':17A,20A 'broker':8A 'cve':15A,18A 'file':7A 'free':5A 'gain':13A 'let':9A 'local':11A 'privileg':14A 'use':3A 'use-after-fre':2A 'user':12A 'window':1A","search_b":"'-10':60B '-11':59B '2026':54B,58B 'affect':66B 'authent':43B 'bfs.sys':21B,39B 'broker':36B 'build':67B 'could':62B 'escal':26B 'exploit':74B 'file':37B 'found':78B 'free':32B 'gain':45B 'higher':46B 'infrastructur':22B 'kb':69B 'let':40B 'list':49B 'local':24B,42B 'local-privilege-escal':23B 'microsoft':48B 'msrc':72B 'novemb':53B 'number':70B 'poc':77B 'privileg':25B,47B 'public':76B 'read':64B 'releas':57B 'secur':55B 'system':38B 'updat':56B 'use':30B 'use-after-fre':29B 'user':44B 'window':27B,35B","search_c":"'allow':87C 'attack':90C 'author':89C 'broker':84C 'elev':92C 'file':85C 'free':81C 'local':94C 'privileg':93C 'system':86C 'use':79C 'window':83C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T19:21:54+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-2026-95979","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-95979","severity":null,"published_at":"2026-11-10T19:21:54+00:00","modified_at":"2026-11-10T19:21:54+00:00","first_seen_at":"2026-11-10T19:25:26+00:00","fetched_at":"2026-11-10T19:25:26+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-95979:2629","url":"https://api.msrc.microsoft.com/cvrf/v3.0/updates/CVE-2026-95979","severity":null,"published_at":"2026-11-10T20:15:47+00:00","modified_at":"2026-11-10T20:15:47+00:00","first_seen_at":"2026-11-10T20:15:47+00:00","fetched_at":"2026-11-10T20:15:47+00:00","note":"MSRC API index lists the CVE in the November 2026 Security Updates (released 2026-11-10). The MSRC UI page and the CVRF document returned no content, so affected builds and KB numbers are not confirmed. Not verified; no exploitation or PoC found. Related bfs.sys UAF write-ups cover other CVEs.","cites":["https://api.msrc.microsoft.com/cvrf/v3.0/updates/CVE-2026-95979"]}],"documents":[{"id":117958,"url":"https://api.msrc.microsoft.com/cvrf/v3.0/updates/CVE-2026-95979","title":"MSRC CVRF update index for CVE-2026-95979 (November 2026 Security Updates)","kind":"advisory","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"advisory","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"}