CVE-2026-72492 (GCVE-0-2026-72492)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:57 – Updated: 2026-08-17 05:44
VLAI
Title
ksmbd: fix use-after-free in same_client_has_lease()
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in same_client_has_lease() same_client_has_lease() returns an opinfo pointer from ci->m_op_list after dropping ci->m_lock without taking a reference. smb_grant_oplock() then dereferences that pointer in copy_lease() and when checking breaking_cnt. A concurrent close can remove the old lease from ci->m_op_list and drop the last reference before the caller uses the returned pointer, leading to a use-after-free. Take a reference when same_client_has_lease() selects an existing lease, drop any previous match while scanning, and release the returned reference in smb_grant_oplock() after copying the lease state.
Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < aaa3bb2bbf2ccbfea9e4e0b9dabf3afc60b50cd0 (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 09634cd055d9bd8dd167995ea52bcd8028dd5dac (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 7c3264d273d524aa6adcce23c01087271f13586f (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 79c7c59bb519db6f5a2a151965e825ec725614cc (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 35d3d6ff2bc1e7aaecb15d5377ebbd6227acae0d (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 0ff82a9cf9312678d8bc4edeef0b6e82659ac12a (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 65b655f65c3ca1ab5d598d3832bb0ff531725858 (git)
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Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 5.15.212 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (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)
guessed Create a notification for this product.
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free in same_client_has_lease()\n\nsame_client_has_lease() returns an opinfo pointer from ci-\u003em_op_list\nafter dropping ci-\u003em_lock without taking a reference.\n\nsmb_grant_oplock() then dereferences that pointer in copy_lease() and\nwhen checking breaking_cnt. A concurrent close can remove the old lease\nfrom ci-\u003em_op_list and drop the last reference before the caller uses\nthe returned pointer, leading to a use-after-free.\n\nTake a reference when same_client_has_lease() selects an existing lease,\ndrop any previous match while scanning, and release the returned\nreference in smb_grant_oplock() after copying the lease state."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
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            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - ksmbd is the in-kernel SMB server on TCP/445; the UAF is reached when a remote client sends SMB2_CREATE with a lease context, handled via ksmbd_conn_handler_loop() through smb2_open() and smb_grant_oplock() into same_client_has_lease().\nAC:L - The attacker controls both sides of the race by holding a leased open on one SMB connection while concurrently issuing SMB2_CREATE (lease upgrade) and SMB2_CLOSE on another connection or channel; no victim-dependent timing or memory layout is required.\nPR:L - Exploitation requires a valid SMB2 session, tree connect, and share permission to open/close the target file with SMB3 leasing enabled; smb2_check_user_session() rejects SMB2_CREATE without SMB2_SESSION_VALID, so this is not reachable on pre-authentication negotiate/echo paths.\nUI:N - No victim interaction is required; the attacker drives all SMB2_CREATE and SMB2_CLOSE operations on their own client connection(s) to trigger the concurrent lease lookup and file close.\nS:U - Impact is kernel heap corruption and privilege escalation on the SMB server host within the ksmbd/kernel security authority; it does not cross a VM, container, or IOMMU boundary.\nC:H - Use-after-free of a freed oplock_info/lease object in copy_lease() reads attacker-influenced slab contents (level, lease state, keys, flags, epoch), enabling kernel memory disclosure and arbitrary-read primitive construction.\nI:H - The UAF dereferences freed oplock_info and embedded lease pointers during copy_lease() and breaking_cnt checks, enabling heap grooming and memory corruption exploitable for arbitrary write or control-flow hijack as root.\nA:H - Concurrent close can free the oplock_info before smb_grant_oplock() uses it, causing reliable kernel memory corruption, oops, or panic and repeatable remote denial of service against the server."
            }
          ]
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      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:44:53.329Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/09634cd055d9bd8dd167995ea52bcd8028dd5dac"
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        {
          "url": "https://git.kernel.org/stable/c/65b655f65c3ca1ab5d598d3832bb0ff531725858"
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      ],
      "title": "ksmbd: fix use-after-free in same_client_has_lease()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72492",
    "datePublished": "2026-08-15T05:57:26.967Z",
    "dateReserved": "2026-08-09T03:40:39.936Z",
    "dateUpdated": "2026-08-17T05:44:53.329Z",
    "state": "PUBLISHED"
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free in same_client_has_lease()\n\nsame_client_has_lease() returns an opinfo pointer from ci-\u003em_op_list\nafter dropping ci-\u003em_lock without taking a reference.\n\nsmb_grant_oplock() then dereferences that pointer in copy_lease() and\nwhen checking breaking_cnt. A concurrent close can remove the old lease\nfrom ci-\u003em_op_list and drop the last reference before the caller uses\nthe returned pointer, leading to a use-after-free.\n\nTake a reference when same_client_has_lease() selects an existing lease,\ndrop any previous match while scanning, and release the returned\nreference in smb_grant_oplock() after copying the lease state."
          }
        ],
        "id": "CVE-2026-72492",
        "lastModified": "2026-08-17T06:19:17.553",
        "metrics": {
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            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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              "type": "Secondary"
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          },
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          }
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T07:19:07+00:00",
      "cve": "CVE-2026-72492",
      "id": "CVE-2026-72492",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: fix use-after-free in same_client_has_lease()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72492.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T01:25:06Z",
      "cve": "CVE-2026-72492",
      "id": "CVE-2026-72492",
      "initial_release_date": "2026-08-27T00:23:13Z",
      "product_status:known_affected": "123",
      "product_status:known_not_affected": "239",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72492",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72492.json",
      "version": "4"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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