{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89636", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.739Z", "datePublished": "2026-09-11T19:45:30.283Z", "dateUpdated": "2026-10-19T08:50:08.281Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:50:08.281Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: clear ce->tgthint in free_tgts()\n\nWhen free_tgts() frees all structures in ce->tlist, ce->tgthint\nis left pointing to one of the freed cache_dfs_tgt structures.\n\nIf ce->tgthint is not reset before it is used later, it results\nin a use-after-free.\n\nSet ce->tgthint to NULL in free_tgts() after the elements are\nfreed to reflect that no elements remain." } ], "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 dangling ce->tgthint is created while handling FSCTL_DFS_GET_REFERRALS/TRANS2_GET_DFS_REFERRAL replies from a remote SMB server over TCP/445 (smb2_get_dfs_refer → cache_refresh_path → update_cache_entry_locked → free_tgts). A malicious, compromised, or MITM'd DFS server reaches this purely over the network.\nAC:L - A hostile DFS server controls referral TTL (down to CACHE_MIN_TTL), target lists, and TCP resets that drive dfs_cache_refresh and reconnect into update_cache_entry_locked; after free_tgts() the later get_tgt_name()/dfs_cache_noreq_update_tgthint() use is deterministic, and the attacker can size and retry referrals to leave the stale hint and reclaim the slab.\nPR:N - The attacker is the remote SMB/DFS peer (or a MITM on an unsigned session) and needs no account, capability, or local privileges on the victim; the client authenticates to that server, and the kernel DFS cache parses the reply regardless of which local user owns the mount.\nUI:N - Once a DFS CIFS mount exists (fstab, autofs/systemd automount, enterprise DFS, cifsroot), dfs_cache_refresh delayed work and reconnect-driven cifs_tree_connect()/dfs_cache_noreq_find() use the stale tgthint automatically after a server-induced refresh or TCP drop, with no further user action.\nS:U - The use-after-free is of kmalloc'd cache_dfs_tgt objects in the client kernel heap and remains in the same host kernel security authority; it does not cross a VM, IOMMU, or sandbox boundary.\nC:H - get_tgt_name() and dfs_cache_noreq_update_tgthint() dereference the freed cache_dfs_tgt (t->name). Reclaiming that slab with attacker-controlled SMB allocations yields an arbitrary kernel read via kstrdup/strcasecmp of a sprayed name pointer.\nI:H - Use-after-free of the heap cache_dfs_tgt enables heap spraying and overlapping live objects; the dangling hint is also copied into DFS referral state and used for failover tree-connect, giving a write/control-flow primitive once the object is reclaimed.\nA:H - Dereferencing the freed cache_dfs_tgt from reconnect (cifs_tree_connect → dfs_cache_noreq_find) or dfs_cache_find oopses or panics the client kernel, and a malicious server can retrigger it on every refresh or reconnect." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/dfs_cache.c" ], "versions": [ { "version": "54be1f6c1c37498bba557049df646cc239fa37e3", "lessThan": "14f60e959b5ac813715ff72e127beb3584ddabf6", "status": "affected", "versionType": "git" }, { "version": "54be1f6c1c37498bba557049df646cc239fa37e3", "lessThan": "3ff9462bb7a06d8d32a1dc02d39580b078ec9e55", "status": "affected", "versionType": "git" }, { "version": "54be1f6c1c37498bba557049df646cc239fa37e3", "lessThan": "7507bd1885643d0461a6017767492450af1ce2a3", "status": "affected", "versionType": "git" }, { "version": "54be1f6c1c37498bba557049df646cc239fa37e3", "lessThan": "9ab46a13798a61d9d020b01d4e57efdabe6624fa", "status": "affected", "versionType": "git" }, { "version": "54be1f6c1c37498bba557049df646cc239fa37e3", "lessThan": "5baab40404a9393bcc0b7b8f1950bf2c307e0984", "status": "affected", "versionType": "git" }, { "version": "54be1f6c1c37498bba557049df646cc239fa37e3", "lessThan": "b1b741cf8e7ce1b91d937e23decd3d3358748700", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/dfs_cache.c" ], "versions": [ { "version": "5.0", "status": "affected" }, { "version": "0", "lessThan": "5.0", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "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": "5.0", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/14f60e959b5ac813715ff72e127beb3584ddabf6" }, { "url": "https://git.kernel.org/stable/c/3ff9462bb7a06d8d32a1dc02d39580b078ec9e55" }, { "url": "https://git.kernel.org/stable/c/7507bd1885643d0461a6017767492450af1ce2a3" }, { "url": "https://git.kernel.org/stable/c/9ab46a13798a61d9d020b01d4e57efdabe6624fa" }, { "url": "https://git.kernel.org/stable/c/5baab40404a9393bcc0b7b8f1950bf2c307e0984" }, { "url": "https://git.kernel.org/stable/c/b1b741cf8e7ce1b91d937e23decd3d3358748700" } ], "title": "smb: client: clear ce->tgthint in free_tgts()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-89636", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:24:47.621556Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:45.662Z" } } ] } }