{ "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": "2026-10-19T09:15:06.742Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:15:06.742Z" }, "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", "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" }, { "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" } } } }