{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98175","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.322Z","datePublished":"2026-10-06T08:44:19.155Z","dateUpdated":"2026-10-07T06:49:24.554Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-07T06:49:24.554Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: cancel reconnect work in clean_demultiplex_info()\n\nclean_demultiplex_info() cancels server->echo delayed work but not\nserver->reconnect, which can cause a use-after-free when the\ndemultiplex thread exits while a reconnect work is still queued:\n\n  cifs_demultiplex_thread()\n    cifs_readv_from_socket()\n      cifs_reconnect()\n        __cifs_reconnect()\n          cifs_queue_server_reconn()\n            mod_delayed_work(cifsiod_wq, &server->reconnect, 0)\n    clean_demultiplex_info()\n      cancel_delayed_work_sync(&server->echo)   // echo canceled\n                                                 // reconnect NOT canceled\n      kfree_sensitive(server)                    // server freed\n\n  ...later, on cifsiod_wq:\n\n  smb2_reconnect_server()\n    server->srv_count  // UAF read of freed server\n\nFix this by canceling server->reconnect delayed work in\nclean_demultiplex_info() before the server is freed, the same way\ncifs_put_tcp_session() already does."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The SMB server at the other end of the client's TCP connection triggers the bug. When it resets the connection or sends an oversized SMB response, cifs_demultiplex_thread() calls cifs_reconnect() and then __cifs_reconnect(), which queues server->reconnect via cifs_queue_server_reconn(). clean_demultiplex_info() then frees the server without cancelling that work.\nAC:H - The malicious server can force reconnects whenever it likes. The free, though, only happens when the client drops its last TCP session reference (umount or a session put, via cifs_put_tcp_session) inside the window where __cifs_reconnect has re-queued the reconnect work. Then smb2_reconnect_server must run after kfree(server). The server cannot produce that client-side timing on demand.\nPR:N - A remote SMB server needs no credentials on the client host to drop its own connection or send a malformed response that drives the client into __cifs_reconnect. Mounting locally is not a lower-privilege route: cifs_fs_type has no FS_USERNS_MOUNT, so a local attacker would need real CAP_SYS_ADMIN.\nUI:R - The client has to mount a share from the attacker's SMB server, and a demultiplex thread only exists after that mount. The free also needs the client to unmount or otherwise drop the session at the wrong moment.\nS:U - The freed struct TCP_Server_Info and the cifsiod_wq worker that uses it after free are both in the client kernel. No VM, IOMMU or sandbox boundary is crossed.\nC:H - smb2_reconnect_server() reads server->srv_count from the freed TCP_Server_Info. If a reallocated object puts a nonzero value there, the worker carries on and dereferences primary_server, the reconnect_mutex and the session lists, all of which a heap spray would control.\nI:H - With a nonzero srv_count in reclaimed memory, the worker increments it, takes reconnect_mutex, manipulates the ses and tcon lists and calls cifs_put_tcp_session on the stale pointer. Those are writes through attacker-shaped memory, so they can corrupt kernel data.\nA:H - syzbot reproduced this use-after-free of TCP_Server_Info in smb2_reconnect_server. A stale worker running on the shared cifsiod_wq workqueue can oops or panic the client kernel."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/connect.c"],"versions":[{"version":"53e0e11efe9289535b060a51d4cf37c25e0d0f2b","lessThan":"180380272f116dbd2b0354c5c7872e112e519149","status":"affected","versionType":"git"},{"version":"53e0e11efe9289535b060a51d4cf37c25e0d0f2b","lessThan":"e3f6a779433d13aafb5edab59e4f9313051e8a52","status":"affected","versionType":"git"},{"version":"53e0e11efe9289535b060a51d4cf37c25e0d0f2b","lessThan":"7ab9ceedd860216fb97f2d8574cbe58b8906f42a","status":"affected","versionType":"git"},{"version":"53e0e11efe9289535b060a51d4cf37c25e0d0f2b","lessThan":"2e5103e11a17c274715dd56cf185eeedccf686b8","status":"affected","versionType":"git"},{"version":"53e0e11efe9289535b060a51d4cf37c25e0d0f2b","lessThan":"c65eae6f61d1778ff7a82e4aae4080e26f486af1","status":"affected","versionType":"git"},{"version":"e008a962311a875a828cbae54b43285858aaa6c8","status":"affected","versionType":"git"},{"version":"123b228a09b90b50b0a9d6eb8294cf0c42efc029","status":"affected","versionType":"git"},{"version":"0ba4c6eaaacbcc4b18f51bb3b1567c65a8fecca9","status":"affected","versionType":"git"},{"version":"d0d2a4c82942e2f51e4984beea1f7e5a994bd06c","status":"affected","versionType":"git"},{"version":"15a12fbbf365a483b1c19f9caeb707b3bea77e10","status":"affected","versionType":"git"},{"version":"f0b715409cb9cf7e21e690f9b163047739761962","status":"affected","versionType":"git"},{"version":"ff04da387c10b6bf7b510392742c8cd46c130fd6","status":"affected","versionType":"git"},{"version":"48f9526f4dcb4b132fe0dc2450835311e3b013a6","status":"affected","versionType":"git"},{"version":"3.10.107","lessThan":"3.11","status":"affected","versionType":"semver"},{"version":"3.12.70","lessThan":"3.13","status":"affected","versionType":"semver"},{"version":"3.16.42","lessThan":"3.17","status":"affected","versionType":"semver"},{"version":"3.18.47","lessThan":"3.19","status":"affected","versionType":"semver"},{"version":"4.1.38","lessThan":"4.2","status":"affected","versionType":"semver"},{"version":"4.4.40","lessThan":"4.5","status":"affected","versionType":"semver"},{"version":"4.8.16","lessThan":"4.9","status":"affected","versionType":"semver"},{"version":"4.9.1","lessThan":"4.10","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/connect.c"],"versions":[{"version":"4.10","status":"affected"},{"version":"0","lessThan":"4.10","status":"unaffected","versionType":"semver"},{"version":"6.6.158","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.112","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.54","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.8","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc4","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.18.54"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"7.2.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"7.3-rc4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10.107"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.12.70"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18.47"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/180380272f116dbd2b0354c5c7872e112e519149"},{"url":"https://git.kernel.org/stable/c/e3f6a779433d13aafb5edab59e4f9313051e8a52"},{"url":"https://git.kernel.org/stable/c/7ab9ceedd860216fb97f2d8574cbe58b8906f42a"},{"url":"https://git.kernel.org/stable/c/2e5103e11a17c274715dd56cf185eeedccf686b8"},{"url":"https://git.kernel.org/stable/c/c65eae6f61d1778ff7a82e4aae4080e26f486af1"}],"title":"smb: client: cancel reconnect work in clean_demultiplex_info()","x_generator":{"engine":"bippy-1.2.0"}}}}