{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31444", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.090Z", "datePublished": "2026-04-22T13:53:41.351Z", "dateUpdated": "2026-08-05T12:22:35.585Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:22:35.585Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free and NULL deref in smb_grant_oplock()\n\nsmb_grant_oplock() has two issues in the oplock publication sequence:\n\n1) opinfo is linked into ci->m_op_list (via opinfo_add) before\n add_lease_global_list() is called. If add_lease_global_list()\n fails (kmalloc returns NULL), the error path frees the opinfo\n via __free_opinfo() while it is still linked in ci->m_op_list.\n Concurrent m_op_list readers (opinfo_get_list, or direct iteration\n in smb_break_all_levII_oplock) dereference the freed node.\n\n2) opinfo->o_fp is assigned after add_lease_global_list() publishes\n the opinfo on the global lease list. A concurrent\n find_same_lease_key() can walk the lease list and dereference\n opinfo->o_fp->f_ci while o_fp is still NULL.\n\nFix by restructuring the publication sequence to eliminate post-publish\nfailure:\n\n- Set opinfo->o_fp before any list publication (fixes NULL deref).\n- Preallocate lease_table via alloc_lease_table() before opinfo_add()\n so add_lease_global_list() becomes infallible after publication.\n- Keep the original m_op_list publication order (opinfo_add before\n lease list) so concurrent opens via same_client_has_lease() and\n opinfo_get_list() still see the in-flight grant.\n- Use opinfo_put() instead of __free_opinfo() on err_out so that\n the RCU-deferred free path is used.\n\nThis also requires splitting add_lease_global_list() to take a\npreallocated lease_table and changing its return type from int to void,\nsince it can no longer fail." } ], "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 - The vulnerable path is reachable through ksmbd over SMB on TCP/445 via SMB2 CREATE/open requests carrying lease contexts.\nAC:L - An attacker can drive the relevant lease/oplock publication races with concurrent SMB opens and attacker-chosen lease keys/client GUIDs; no condition outside attacker influence is required for the NULL dereference path.\nPR:N - Although SMB2 CREATE requires a valid session and tree connection, ksmbd supports guest/anonymous sessions and guest shares, making unauthenticated remote triggering reasonable in exposed deployments.\nUI:N - No victim user action is needed once the ksmbd service and share are reachable; the attacker sends SMB protocol requests directly.\nS:U - The vulnerability affects the kernel SMB server within the same host security authority and does not cross a separate security boundary such as a VM escape.\nC:H - The bug includes a use-after-free of struct oplock_info left reachable from shared lists, which can plausibly be leveraged for kernel memory disclosure through heap reuse.\nI:H - The use-after-free is kernel memory corruption in a network-reachable path and can plausibly be exploited for control-flow or data-structure corruption.\nA:H - Both the NULL dereference and use-after-free can crash or oops the kernel, causing high availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/oplock.c" ], "versions": [ { "version": "302fef75512b2c8329a3f5efab1ae7ba2562387a", "lessThan": "9e785f004cbc56390479b77375726ea9b0d1a8a6", "status": "affected", "versionType": "git" }, { "version": "08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c", "lessThan": "7de55bba69cbf0f9280daaea385daf08bc076121", "status": "affected", "versionType": "git" }, { "version": "1d6abf145615dbfe267ce3b0a271f95e3780e18e", "lessThan": "a5c6f6d6ceefed2d5210ee420fb75f8362461f46", "status": "affected", "versionType": "git" }, { "version": "ce8507ee82c888126d8e7565e27c016308d24cde", "lessThan": "6d7e5a918c1d0aad06db0e17677b66fc9a471021", "status": "affected", "versionType": "git" }, { "version": "1dfd062caa165ec9d7ee0823087930f3ab8a6294", "lessThan": "48623ec358c1c600fa1e38368746f933e0f1a617", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/oplock.c" ], "versions": [ { "version": "6.6.130", "lessThan": "6.6.131", "status": "affected", "versionType": "semver" }, { "version": "6.12.78", "lessThan": "6.12.80", "status": "affected", "versionType": "semver" }, { "version": "6.18.19", "lessThan": "6.18.21", "status": "affected", "versionType": "semver" }, { "version": "6.19.9", "lessThan": "6.19.11", "status": "affected", "versionType": "semver" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.130", "versionEndExcluding": "6.6.131" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.78", "versionEndExcluding": "6.12.80" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18.19", "versionEndExcluding": "6.18.21" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19.9", "versionEndExcluding": "6.19.11" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/9e785f004cbc56390479b77375726ea9b0d1a8a6" }, { "url": "https://git.kernel.org/stable/c/7de55bba69cbf0f9280daaea385daf08bc076121" }, { "url": "https://git.kernel.org/stable/c/a5c6f6d6ceefed2d5210ee420fb75f8362461f46" }, { "url": "https://git.kernel.org/stable/c/6d7e5a918c1d0aad06db0e17677b66fc9a471021" }, { "url": "https://git.kernel.org/stable/c/48623ec358c1c600fa1e38368746f933e0f1a617" } ], "title": "ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()", "x_generator": { "engine": "bippy-1.2.0" } } } }