{"id":"CVE-2026-99114","kind":"vulnerability","aliases":["CVE-2026-99114"],"related":[],"title":"Linux kernel ksmbd: uninitialized memory returned in SMB filesystem control info","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: initialize FileSystemControlFlags in FS_CONTROL_INFORMATION\n\nsmb2_get_info_filesystem() reports 48 bytes for FS_CONTROL_INFORMATION,\nthat is the whole of struct smb2_fs_control_info, but never assigns\nFileSystemControlFlags.  Those four bytes go to the client as they are\nfound in the response buffer.\n\nThe buffer is zeroed on allocation, so a standalone request leaks\nnothing.  A compound request can leak: the offset of the next response\nis advanced by the length pinned for the previous one, so a reply that\nwas written into the buffer and then dropped in favour of the short\nerror response of smb2_set_err_rsp() stays there, and the next reply is\nlaid over it with only the header cleared.\n\nksmbd does not implement quota tracking, so report no control flags.","summary":"In the ksmbd SMB server in the Linux kernel, the FS_CONTROL_INFORMATION reply never sets FileSystemControlFlags, so four bytes of leftover response-buffer memory are sent to the client. In a compound request, stale data from a dropped earlier reply can be carried into the next response.","severity":"low","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["file-server","ksmbd","linux-kernel","runtime","self-hosted"],"not_affected_if":["ksmbd-not-enabled","samba-userspace"],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-10-28T11:17:30+00:00","first_seen_at":"2026-10-28T11:32:34+00:00","triaged_at":"2026-10-28T11:37:40+00:00","updated_at":"2026-10-28T11:37:40+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-10-28T11:37:40Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Linux kernel ksmbd: uninitialized memory returned in SMB filesystem control info","impact":"low","summary":"In the ksmbd SMB server in the Linux kernel, the FS_CONTROL_INFORMATION reply never sets FileSystemControlFlags, so four bytes of leftover response-buffer memory are sent to the client. In a compound request, stale data from a dropped earlier reply can be carried into the next response.","category":"runtime","nicknames":[],"who_cares":["linux-kernel","ksmbd","self-hosted","file-server"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Client reads leftover kernel memory bytes from SMB responses","analyst_note":"Check the NVD entry and the upstream kernel commit for affected and fixed kernel versions, and whether an authenticated session is required.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["ksmbd-not-enabled","samba-userspace"],"who_is_affected":"Systems running the ksmbd in-kernel SMB server on a Linux kernel that does not include the upstream fix. Hosts that do not run ksmbd (for example, those using Samba's userspace smbd) are not affected by this flaw. The sources do not list affected kernel versions.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"low"},"cost_usd":0.0006,"input_tokens":3520,"output_tokens":496,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':13A,16A '-99114':14A,17A '48':100C 'advanc':159C 'alloc':140C 'assign':118C 'buffer':53B,134C,136C,176C 'byte':48B,101C,122C 'carri':73B 'clear':206C 'client':59B,126C 'compound':62B,148C 'control':10A,40B,93C,104C,114C,216C 'cve':12A,15A 'data':65B 'drop':68B,179C 'earlier':69B 'err':190C 'error':185C 'favour':181C 'file':19B 'file-serv':18B 'filesystem':9A,98C 'filesystemcontrolflag':45B,90C,119C 'flag':217C 'follow':83C 'found':130C 'four':47B,121C 'fs':39B,92C,103C,113C 'get':96C 'go':123C 'header':205C 'host':28B 'implement':210C 'info':11A,97C,115C 'inform':41B,94C,105C 'initi':89C 'kernel':2A,24B,37B,81C 'ksmbd':3A,21B,31B,88C,207C 'laid':199C 'leak':145C,151C 'leftov':50B 'length':162C 'linux':1A,23B,36B,80C 'linux-kernel':22B 'memori':5A,54B 'never':43B,117C 'next':76B,156C,196C 'noth':146C 'offset':153C 'one':167C 'pin':163C 'previous':166C 'quota':211C 'repli':42B,70B,170C,197C 'report':99C,214C 'request':63B,144C,149C 'resolv':87C 'respons':52B,77B,133C,157C,186C 'response-buff':51B 'return':6A 'rsp':191C 'runtim':25B 'self':27B 'self-host':26B 'sent':56B 'server':20B,33B 'set':44B,189C 'short':184C 'smb':8A,32B 'smb2':95C,112C,188C 'stale':64B 'standalon':143C 'stay':192C 'struct':111C 'track':212C 'uniniti':4A 'vulner':84C 'whole':109C 'written':173C 'zero':138C","nicknames":[],"mitigations":[],"who_affected":"Systems running the ksmbd in-kernel SMB server on a Linux kernel that does not include the upstream fix. Hosts that do not run ksmbd (for example, those using Samba's userspace smbd) are not affected by this flaw. The sources do not list affected kernel versions.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-28T11:17:30+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-99114","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99114","severity":null,"published_at":"2026-10-28T11:17:30+00:00","modified_at":"2026-10-28T11:17:30+00:00","first_seen_at":"2026-10-28T11:32:34+00:00","fetched_at":"2026-10-28T11:32:34+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}