{"id":"CVE-2026-98681","kind":"vulnerability","aliases":["CVE-2026-98681"],"related":[],"title":"Linux kernel SMB client: shared bitfield flags race and corrupt state","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: split cifsFileInfo bitfields to avoid shared-byte RMW races\n\nThe invalidHandle, swapfile, oplock_break_cancelled, offload,\nand status_file_deleted fields are stored in the same bitfield byte\nin struct cifsFileInfo, but are updated in different code paths that\nmay run simultaneously, and are protected by different locks.  Since\nbitfield assignments generate byte-level read-modify-write operations,\na modification to one flag can overwrite a concurrent modification to\nanother flag.\n\nTo avoid these races, convert these flags from a bitfield to\nseparate bool fields.","summary":"In the Linux kernel's CIFS/SMB client, several flags in struct cifsFileInfo share one bitfield byte but are updated under different locks, so concurrent writes can overwrite each other. The sources describe a memory-corruption-style race in kernel state but do not state a concrete attacker outcome.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["cifs","linux-kernel","other","smb-client"],"not_affected_if":[],"how_to_check":"- unknown","fix":"- unknown","status":"open","published_at":"2026-10-18T16:17:21+00:00","first_seen_at":"2026-10-23T21:57:16+00:00","triaged_at":"2026-10-25T05:19:13+00:00","updated_at":"2026-10-25T05:19:13+00:00","category":"other","confidence":0.4,"triage":{"at":"2026-10-25T05:19:13Z","model":"claude-haiku-5-5","output":{"fix":"- unknown","reach":"unknown","title":"Linux kernel SMB client: shared bitfield flags race and corrupt state","impact":"medium","summary":"In the Linux kernel's CIFS/SMB client, several flags in struct cifsFileInfo share one bitfield byte but are updated under different locks, so concurrent writes can overwrite each other. The sources describe a memory-corruption-style race in kernel state but do not state a concrete attacker outcome.","category":"other","nicknames":[],"who_cares":["linux-kernel","smb-client","cifs"],"confidence":0.4,"needs_auth":"unknown","worst_case":"unknown","analyst_note":"Check the kernel stable commit and NVD entry for the affected kernel version ranges and whether the race has a practical exploit path for CIFS mounts.","how_to_check":"- unknown","needs_analyst":true,"not_affected_if":[],"who_is_affected":"unknown","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000528,"input_tokens":3440,"output_tokens":369,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':13A,16A '-98681':14A,17A 'anoth':159C 'assign':138C 'attack':73B 'avoid':91C,162C 'bitfield':6A,40B,89C,114C,137C,170C 'bool':173C 'break':101C 'byte':41B,94C,115C,141C 'byte-level':140C 'cancel':102C 'cif':18B 'cifs/smb':31B 'cifsfileinfo':37B,88C,118C 'client':4A,25B,32B,86C 'code':124C 'concret':72B 'concurr':49B,156C 'convert':165C 'corrupt':10A,61B 'cve':12A,15A 'delet':107C 'describ':57B 'differ':46B,123C,134C 'field':108C,174C 'file':106C 'flag':7A,34B,152C,160C,167C 'follow':80C 'generat':139C 'invalidhandl':98C 'kernel':2A,21B,29B,65B,78C 'level':142C 'linux':1A,20B,28B,77C 'linux-kernel':19B 'lock':47B,135C 'may':127C 'memori':60B 'memory-corruption-styl':59B 'modif':149C,157C 'modifi':145C 'offload':103C 'one':39B,151C 'oper':147C 'oplock':100C 'outcom':74B 'overwrit':52B,154C 'path':125C 'protect':132C 'race':8A,63B,96C,164C 'read':144C 'read-modify-writ':143C 'resolv':84C 'rmw':95C 'run':128C 'separ':172C 'sever':33B 'share':5A,38B,93C 'shared-byt':92C 'simultan':129C 'sinc':136C 'smb':3A,24B,85C 'smb-client':23B 'sourc':56B 'split':87C 'state':11A,66B,70B 'status':105C 'store':110C 'struct':36B,117C 'style':62B 'swapfil':99C 'updat':44B,121C 'vulner':81C 'write':50B,146C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-18T16:17:21+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-98681","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98681","severity":null,"published_at":"2026-10-18T16:17:21+00:00","modified_at":"2026-10-21T13:21:37+00:00","first_seen_at":"2026-10-23T21:57:16+00:00","fetched_at":"2026-10-23T22:28:56+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"}