{"id":"CVE-2026-99280","kind":"vulnerability","aliases":["CVE-2026-99280"],"related":[],"title":"Linux kernel ksmbd: session procfs race can crash the SMB server","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: drain session procfs readers before dropping table references\n\nSession registration failure and connection cleanup can drop the table\nreference while the per-session procfs entry is still accessible. If a\nreader holds the last remaining reference, its final put calls\nproc_remove() from its own callback and waits for that callback to\nfinish.\n\nRemove the procfs entry before dropping the table reference in the\nregistration failure path. Queue sessions removed during connection\ncleanup and drain their procfs readers after releasing both session\nlocks, then return their table references. Keep the global hash node\nunhashed while a session is queued so a concurrent unregister cannot\ndrop the reference again.\n\nPrevious-session replacement also destroys the file table before the\nsession is finally freed. Detach the idr under the lock used by procfs\nfile counters, and report zero files after it has been detached. This\nprevents a reader from accessing the idr during or after its\ndestruction.","summary":"A race in the Linux kernel's ksmbd SMB file server lets session cleanup remove procfs entries while a reader still uses them, which can corrupt memory. The sources do not state what an attacker can gain beyond a crash or instability.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["ksmbd","linux","runtime","self-hosted","smb"],"not_affected_if":["ksmbd-not-loaded","samba-only"],"how_to_check":"- Check whether the kernel has the ksmbd module loaded, for example with `lsmod | grep ksmbd`.\n- Check the running kernel version with `uname -r` and compare it with the fixed kernel in the kernel.org stable branch the distribution ships.","fix":null,"status":"open","published_at":"2026-11-07T14:17:03+00:00","first_seen_at":"2026-11-07T14:47:40+00:00","triaged_at":"2026-11-07T14:49:49+00:00","updated_at":"2026-11-07T14:49:49+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-11-07T14:49:49Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Linux kernel ksmbd: session procfs race can crash the SMB server","impact":"medium","summary":"A race in the Linux kernel's ksmbd SMB file server lets session cleanup remove procfs entries while a reader still uses them, which can corrupt memory. The sources do not state what an attacker can gain beyond a crash or instability.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["linux","ksmbd","smb","self-hosted"],"confidence":0.5,"fix_status":"unknown","needs_auth":"unknown","worst_case":"Kernel memory corruption or crash during SMB session teardown","analyst_note":"Confirm affected kernel version ranges and fixed commits from the kernel.org CVE record and NVD entry for CVE-2026-99280.","how_to_check":"- Check whether the kernel has the ksmbd module loaded, for example with `lsmod | grep ksmbd`.\n- Check the running kernel version with `uname -r` and compare it with the fixed kernel in the kernel.org stable branch the distribution ships.","plain_action":"","needs_analyst":true,"not_affected_if":["ksmbd-not-loaded","samba-only"],"who_is_affected":"Systems running the Linux kernel ksmbd SMB server module, which is used to share files over SMB. Hosts that do not load ksmbd are not exposed. The sources do not name affected kernel version ranges.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000717,"input_tokens":4432,"output_tokens":548,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':13A,16A '-99280':14A,17A 'access':106C,227C 'also':191C 'attack':59B 'beyond':62B 'call':118C 'callback':124C,129C 'cannot':182C 'cleanup':38B,91C,151C 'concurr':180C 'connect':90C,150C 'corrupt':50B 'counter':212C 'crash':8A,64B 'cve':12A,15A 'destroy':192C 'destruct':234C 'detach':202C,221C 'drain':78C,153C 'drop':83C,93C,137C,183C 'entri':41B,103C,135C 'failur':88C,144C 'file':34B,194C,211C,216C 'final':116C,200C 'finish':131C 'follow':72C 'freed':201C 'gain':61B 'global':169C 'hash':170C 'hold':110C 'host':23B 'idr':204C,229C 'instabl':66B 'keep':167C 'kernel':2A,30B,70C 'ksmbd':3A,18B,32B,77C 'last':112C 'let':36B 'linux':1A,19B,29B,69C 'lock':161C,207C 'memori':51B 'node':171C 'path':145C 'per':100C 'per-sess':99C 'prevent':223C 'previous':188C 'previous-sess':187C 'proc':119C 'procf':5A,40B,80C,102C,134C,155C,210C 'put':117C 'queu':177C 'queue':146C 'race':6A,26B 'reader':44B,81C,109C,156C,225C 'refer':85C,96C,114C,140C,166C,185C 'registr':87C,143C 'releas':158C 'remain':113C 'remov':39B,120C,132C,148C 'replac':190C 'report':214C 'resolv':76C 'return':163C 'runtim':20B 'self':22B 'self-host':21B 'server':11A,35B 'session':4A,37B,79C,86C,101C,147C,160C,175C,189C,198C 'smb':10A,24B,33B 'sourc':53B 'state':56B 'still':45B,105C 'tabl':84C,95C,139C,165C,195C 'unhash':172C 'unregist':181C 'use':46B,208C 'vulner':73C 'wait':126C 'zero':215C","nicknames":[],"mitigations":[],"who_affected":"Systems running the Linux kernel ksmbd SMB server module, which is used to share files over SMB. Hosts that do not load ksmbd are not exposed. The sources do not name affected kernel version ranges.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["ksmbd","linux","runtime","selfhosted","smb","unknown"],"campaign_type":null,"search_a":"'-2026':13A,16A '-99280':14A,17A 'crash':8A 'cve':12A,15A 'kernel':2A 'ksmbd':3A 'linux':1A 'procf':5A 'race':6A 'server':11A 'session':4A 'smb':10A","search_b":"'attack':59B 'beyond':62B 'cleanup':38B 'corrupt':50B 'crash':64B 'entri':41B 'file':34B 'gain':61B 'host':23B 'instabl':66B 'kernel':30B 'ksmbd':18B,32B 'let':36B 'linux':19B,29B 'memori':51B 'procf':40B 'race':26B 'reader':44B 'remov':39B 'runtim':20B 'self':22B 'self-host':21B 'server':35B 'session':37B 'smb':24B,33B 'sourc':53B 'state':56B 'still':45B 'use':46B","search_c":"'access':106C,227C 'also':191C 'call':118C 'callback':124C,129C 'cannot':182C 'cleanup':91C,151C 'concurr':180C 'connect':90C,150C 'counter':212C 'destroy':192C 'destruct':234C 'detach':202C,221C 'drain':78C,153C 'drop':83C,93C,137C,183C 'entri':103C,135C 'failur':88C,144C 'file':194C,211C,216C 'final':116C,200C 'finish':131C 'follow':72C 'freed':201C 'global':169C 'hash':170C 'hold':110C 'idr':204C,229C 'keep':167C 'kernel':70C 'ksmbd':77C 'last':112C 'linux':69C 'lock':161C,207C 'node':171C 'path':145C 'per':100C 'per-sess':99C 'prevent':223C 'previous':188C 'previous-sess':187C 'proc':119C 'procf':80C,102C,134C,155C,210C 'put':117C 'queu':177C 'queue':146C 'reader':81C,109C,156C,225C 'refer':85C,96C,114C,140C,166C,185C 'registr':87C,143C 'releas':158C 'remain':113C 'remov':120C,132C,148C 'replac':190C 'report':214C 'resolv':76C 'return':163C 'session':79C,86C,101C,147C,160C,175C,189C,198C 'still':105C 'tabl':84C,95C,139C,165C,195C 'unhash':172C 'unregist':181C 'use':208C 'vulner':73C 'wait':126C 'zero':215C","first_public_at":"2026-11-07T14:17:03+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-99280","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99280","severity":null,"published_at":"2026-11-07T14:17:03+00:00","modified_at":"2026-11-07T14:17:03+00:00","first_seen_at":"2026-11-07T14:47:40+00:00","fetched_at":"2026-11-07T14:47:40+00:00","note":null}],"documents":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}