{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31718", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.134Z", "datePublished": "2026-05-01T13:56:12.680Z", "dateUpdated": "2026-08-05T12:24:49.667Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:24:49.667Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger\n\nWhen a durable file handle survives session disconnect (TCP close without\nSMB2_LOGOFF), session_fd_check() sets fp->conn = NULL to preserve the\nhandle for later reconnection. However, it did not clean up the byte-range\nlocks on fp->lock_list.\n\nLater, when the durable scavenger thread times out and calls\n__ksmbd_close_fd(NULL, fp), the lock cleanup loop did:\n\n spin_lock(&fp->conn->llist_lock);\n\nThis caused a slab use-after-free because fp->conn was NULL and the\noriginal connection object had already been freed by\nksmbd_tcp_disconnect().\n\nThe root cause is asymmetric cleanup: lock entries (smb_lock->clist) were\nleft dangling on the freed conn->lock_list while fp->conn was nulled out.\n\nTo fix this issue properly, we need to handle the lifetime of\nsmb_lock->clist across three paths:\n - Safely skip clist deletion when list is empty and fp->conn is NULL.\n - Remove the lock from the old connection's lock_list in\n session_fd_check()\n - Re-add the lock to the new connection's lock_list in\n ksmbd_reopen_durable_fd()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - ksmbd is an in-kernel SMB server reachable over TCP/IP, and the vulnerable durable-handle and byte-range-lock paths are driven by SMB2 network requests.\nAC:L - The attacker can create the durable handle, add a lock, disconnect TCP without SMB2_LOGOFF, and wait for the durable scavenger; no race or condition outside attacker control is required.\nPR:N - The path requires an SMB session and tree connection, but ksmbd supports guest/anonymous sessions and guest shares, making a no-credential network attack a reasonable high-severity deployment scenario.\nUI:N - No victim interaction is required once the ksmbd service is exposed; the attacker sends SMB2 requests and closes the connection.\nS:U - The bug corrupts kernel/ksmbd state within the same security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - This is a kernel use-after-free involving dangling list entries tied to freed connection state, and such memory corruption can plausibly be shaped into kernel memory disclosure.\nI:H - The same UAF/list corruption can plausibly be leveraged for kernel memory corruption or control-flow impact, so high integrity impact is warranted.\nA:H - At minimum, triggering the scavenger cleanup can dereference freed or invalid connection/list state and crash the kernel." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/vfs_cache.c" ], "versions": [ { "version": "8df4bcdb0a4232192b2445256c39b787d58ef14d", "lessThan": "0000a7780e0e446a28a273572f6ea8f7f582f694", "status": "affected", "versionType": "git" }, { "version": "c8efcc786146a951091588e5fa7e3c754850cb3c", "lessThan": "e33c65f011980b4ad4abfd93585ec2079856368f", "status": "affected", "versionType": "git" }, { "version": "c8efcc786146a951091588e5fa7e3c754850cb3c", "lessThan": "3d6682726c2d3a46d31dae88b8166786b09b03ad", "status": "affected", "versionType": "git" }, { "version": "c8efcc786146a951091588e5fa7e3c754850cb3c", "lessThan": "b34fc42cfe922e551f7a27d3ac3bb016e41d7dd9", "status": "affected", "versionType": "git" }, { "version": "c8efcc786146a951091588e5fa7e3c754850cb3c", "lessThan": "235e32320a470fcd3998fb3774f2290a0eb302a1", "status": "affected", "versionType": "git" }, { "version": "6.6.32", "lessThan": "6.6.140", "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/server/vfs_cache.c" ], "versions": [ { "version": "6.9", "status": "affected" }, { "version": "0", "lessThan": "6.9", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.140", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.84", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.25", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.2", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "6.6.32", "versionEndExcluding": "6.6.140" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.12.84" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.18.25" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.0.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0000a7780e0e446a28a273572f6ea8f7f582f694" }, { "url": "https://git.kernel.org/stable/c/e33c65f011980b4ad4abfd93585ec2079856368f" }, { "url": "https://git.kernel.org/stable/c/3d6682726c2d3a46d31dae88b8166786b09b03ad" }, { "url": "https://git.kernel.org/stable/c/b34fc42cfe922e551f7a27d3ac3bb016e41d7dd9" }, { "url": "https://git.kernel.org/stable/c/235e32320a470fcd3998fb3774f2290a0eb302a1" } ], "title": "ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger", "x_generator": { "engine": "bippy-1.2.0" } } } }