CVE-2026-68083 (GCVE-0-2026-68083)

Vulnerability from cvelistv5 – Published: 2026-08-10 11:41 – Updated: 2026-08-17 04:58
VLAI
Title
ksmbd: fix path resolution in ksmbd_vfs_kern_path_create
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix path resolution in ksmbd_vfs_kern_path_create The SMB2 open lookup is rooted at the share with LOOKUP_BENEATH, but the create/mkdir/hardlink sink is not: ksmbd_vfs_kern_path_create() builds an absolute path with convert_to_unix_name() and resolves it from AT_FDCWD via start_creating_path(), so a ".." component is walked from the real filesystem root and escapes the export. An authenticated client races a missing path component so the rooted open lookup returns -ENOENT (taking the create branch) while the same component is present (a directory) when the create walk runs; the create then resolves ".." out of the share. Root the create walk at the share like the lookup and rename paths already are: resolve the parent with vfs_path_parent_lookup(..., LOOKUP_BENEATH, &share_conf->vfs_path) and create the final component with start_creating_noperm(). convert_to_unix_name() then has no callers and is removed.
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 265fd1991c1db85fbabaad4946ca0e63e2ae688d , < 489d1ded01425c0fb33418172c0e4e588467526b (git)
Affected: 265fd1991c1db85fbabaad4946ca0e63e2ae688d , < c7c884a1305aa4540eb7942a50bd356b34120e1f (git)
Affected: 265fd1991c1db85fbabaad4946ca0e63e2ae688d , < 98185b3025beeae92d1fe700d5db26b9ac4bf025 (git)
Affected: 265fd1991c1db85fbabaad4946ca0e63e2ae688d , < 1c8951963d8ed357f70f59e0ad4ddce2199d2016 (git)
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Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
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              "versionType": "semver"
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              "version": "7.2",
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      "cpeApplicability": [
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                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.40",
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix path resolution in ksmbd_vfs_kern_path_create\n\nThe SMB2 open lookup is rooted at the share with LOOKUP_BENEATH, but the\ncreate/mkdir/hardlink sink is not: ksmbd_vfs_kern_path_create() builds an\nabsolute path with convert_to_unix_name() and resolves it from AT_FDCWD\nvia start_creating_path(), so a \"..\" component is walked from the real\nfilesystem root and escapes the export.\n\nAn authenticated client races a missing path component so the rooted open\nlookup returns -ENOENT (taking the create branch) while the same component\nis present (a directory) when the create walk runs; the create then\nresolves \"..\" out of the share.\n\nRoot the create walk at the share like the lookup and rename paths already\nare: resolve the parent with vfs_path_parent_lookup(..., LOOKUP_BENEATH,\n\u0026share_conf-\u003evfs_path) and create the final component with\nstart_creating_noperm(). convert_to_unix_name() then has no callers and is\nremoved."
        }
      ],
      "metrics": [
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "value": "AV:N - ksmbd is the in-kernel SMB server on TCP/445; the flaw is reached from remote SMB2_CREATE (and SMB2_SET_INFO hardlink) requests processed in ksmbd_conn_handler_loop() through smb2_open()/smb2_create_link() into ksmbd_vfs_kern_path_create().\nAC:L - Exploitation requires a TOCTOU race, but the attacker controls both sides by issuing concurrent SMB2_CREATE and directory-creation requests over one or more connections, so success does not depend on conditions outside attacker influence.\nPR:N - SMB2_CREATE requires a valid session, tree connect, and writable share, but ksmbd supports guest/anonymous sessions on writable exports; per kernel CNA precedent, export write access alone is not elevated privilege.\nUI:N - No victim interaction is required; the attacker sends crafted SMB2 protocol requests directly to a reachable ksmbd service without needing another user to mount shares or open files.\nS:U - Impact is confined to the host kernel filesystem namespace managed by ksmbd; escaping an SMB export is not a VM, IOMMU, or separate security-authority boundary crossing.\nC:N - This is a path-resolution logic flaw with no memory corruption, out-of-bounds access, or demonstrated arbitrary read of host files outside the export; impact is unauthorized creation/linking, not information disclosure.\nI:H - ksmbd_vfs_kern_path_create() resolves attacker paths from AT_FDCWD without LOOKUP_BENEATH, letting authenticated clients create files, directories, or hardlinks outside the exported share using the server\u0027s filesystem credentials.\nA:H - Repeated successful escaped creates/mkdirs outside the export can exhaust root-filesystem inodes or storage (especially tmpfs/world-writable targets), causing system-wide service unavailability on affected NAS/cloud hosts."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:58:30.819Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        },
        {
          "url": "https://git.kernel.org/stable/c/1c8951963d8ed357f70f59e0ad4ddce2199d2016"
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      "title": "ksmbd: fix path resolution in ksmbd_vfs_kern_path_create",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68083",
    "datePublished": "2026-08-10T11:41:47.153Z",
    "dateReserved": "2026-07-30T09:28:09.367Z",
    "dateUpdated": "2026-08-17T04:58:30.819Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
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      "date": "2026-09-20",
      "epss": "0.00446",
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        "descriptions": [
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix path resolution in ksmbd_vfs_kern_path_create\n\nThe SMB2 open lookup is rooted at the share with LOOKUP_BENEATH, but the\ncreate/mkdir/hardlink sink is not: ksmbd_vfs_kern_path_create() builds an\nabsolute path with convert_to_unix_name() and resolves it from AT_FDCWD\nvia start_creating_path(), so a \"..\" component is walked from the real\nfilesystem root and escapes the export.\n\nAn authenticated client races a missing path component so the rooted open\nlookup returns -ENOENT (taking the create branch) while the same component\nis present (a directory) when the create walk runs; the create then\nresolves \"..\" out of the share.\n\nRoot the create walk at the share like the lookup and rename paths already\nare: resolve the parent with vfs_path_parent_lookup(..., LOOKUP_BENEATH,\n\u0026share_conf-\u003evfs_path) and create the final component with\nstart_creating_noperm(). convert_to_unix_name() then has no callers and is\nremoved."
          }
        ],
        "id": "CVE-2026-68083",
        "lastModified": "2026-08-17T05:18:07.487",
        "metrics": {
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                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 9.1,
                "baseSeverity": "CRITICAL",
                "confidentialityImpact": "NONE",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "published": "2026-08-10T12:17:20.807",
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        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-10T21:49:31+00:00",
      "cve": "CVE-2026-68083",
      "id": "CVE-2026-68083",
      "initial_release_date": "2026-08-10T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: fix path resolution in ksmbd_vfs_kern_path_create",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68083.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-10T16:42:08Z",
      "cve": "CVE-2026-68083",
      "id": "CVE-2026-68083",
      "initial_release_date": "2026-08-11T23:48:56Z",
      "product_status:known_affected": "30",
      "product_status:known_not_affected": "327",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-68083",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68083.json",
      "version": "5"
    }
  }
}



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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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