Vulnerability-Lookup

FKIE_CVE-2026-90162

Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-09-18 18:17

Severity

8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: ksmbd: defer publishing granted locks to prevent UAF/double-free race In smb2_lock(), mid-batch granted locks are published to connection-wide (conn->lock_list) and file-wide (fp->lock_list) lists immediately upon vfs_lock_file() success, while also remaining tracked on the stack-local rollback_list. If a subsequent element in the same SMB2_LOCK request array fails validation or execution, the thread jumps to out: and walks rollback_list to undo previously granted locks. However, because the granted lock was already published to conn->lock_list, a concurrent UNLOCK request on the same connection can find the lock object and kfree() it before the rollback loop executes. When the granting thread subsequently walks rollback_list, it dereferences and frees the already-freed ksmbd_lock structure, resulting in a Use-After-Free and Double-Free (on both ksmbd_lock and struct file_lock). Fix this by deferring the publication of granted locks to conn->lock_list and fp->lock_list until after the entire array of lock elements has been processed without error. Mid-batch grants remain tracked exclusively on the request-local rollback_list until the whole batch succeeds, eliminating the race window.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/29f74f0f2e6df3b393b7b66e810136d0c64e3c59
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/a1d26dfb32919088e3638dca01068df3c4507433

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a1d26dfb32919088e3638dca01068df3c4507433",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "29f74f0f2e6df3b393b7b66e810136d0c64e3c59",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: defer publishing granted locks to prevent UAF/double-free race\n\nIn smb2_lock(), mid-batch granted locks are published to connection-wide\n(conn-\u003elock_list) and file-wide (fp-\u003elock_list) lists immediately upon\nvfs_lock_file() success, while also remaining tracked on the stack-local\nrollback_list.\n\nIf a subsequent element in the same SMB2_LOCK request array fails\nvalidation or execution, the thread jumps to out: and walks\nrollback_list to undo previously granted locks. However, because the\ngranted lock was already published to conn-\u003elock_list, a concurrent\nUNLOCK request on the same connection can find the lock object and\nkfree() it before the rollback loop executes.\n\nWhen the granting thread subsequently walks rollback_list, it\ndereferences and frees the already-freed ksmbd_lock structure, resulting\nin a Use-After-Free and Double-Free (on both ksmbd_lock and struct\nfile_lock).\n\nFix this by deferring the publication of granted locks to\nconn-\u003elock_list and fp-\u003elock_list until after the entire array of lock\nelements has been processed without error. Mid-batch grants remain\ntracked exclusively on the request-local rollback_list until the whole\nbatch succeeds, eliminating the race window."
    }
  ],
  "id": "CVE-2026-90162",
  "lastModified": "2026-09-18T18:17:44.827",
  "metrics": {
    "cvssMetricV31": [
      {
        "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",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-17T17:17:09.517",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/29f74f0f2e6df3b393b7b66e810136d0c64e3c59"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a1d26dfb32919088e3638dca01068df3c4507433"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-90162 (GCVE-0-2026-90162)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:06 – Updated: 2026-09-18 17:53

Title

ksmbd: defer publishing granted locks to prevent UAF/double-free race

Summary

Severity

8.8 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/a1d26dfb32919088e…
https://git.kernel.org/stable/c/29f74f0f2e6df3b39…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < a1d26dfb32919088e3638dca01068df3c4507433 (git) Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 29f74f0f2e6df3b393b7b66e810136d0c64e3c59 (git)
Linux	Linux	Affected: 5.15 Unaffected: 0 , < 5.15 (semver) Unaffected: 7.2.6 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a1d26dfb32919088e3638dca01068df3c4507433",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "29f74f0f2e6df3b393b7b66e810136d0c64e3c59",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: defer publishing granted locks to prevent UAF/double-free race\n\nIn smb2_lock(), mid-batch granted locks are published to connection-wide\n(conn-\u003elock_list) and file-wide (fp-\u003elock_list) lists immediately upon\nvfs_lock_file() success, while also remaining tracked on the stack-local\nrollback_list.\n\nIf a subsequent element in the same SMB2_LOCK request array fails\nvalidation or execution, the thread jumps to out: and walks\nrollback_list to undo previously granted locks. However, because the\ngranted lock was already published to conn-\u003elock_list, a concurrent\nUNLOCK request on the same connection can find the lock object and\nkfree() it before the rollback loop executes.\n\nWhen the granting thread subsequently walks rollback_list, it\ndereferences and frees the already-freed ksmbd_lock structure, resulting\nin a Use-After-Free and Double-Free (on both ksmbd_lock and struct\nfile_lock).\n\nFix this by deferring the publication of granted locks to\nconn-\u003elock_list and fp-\u003elock_list until after the entire array of lock\nelements has been processed without error. Mid-batch grants remain\ntracked exclusively on the request-local rollback_list until the whole\nbatch succeeds, eliminating the race window."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The attacker-controlled data is the SMB2 LOCK request (struct smb2_lock_req lock elements: Offset, Length, Flags) received on TCP/445 by ksmbd_conn_handler_loop(), queued with queue_ksmbd_work(), and dispatched to smb2_lock() via conn-\u003ecmds[SMB2_LOCK_HE]; the racing free is a second SMB2 LOCK with SMB2_LOCKFLAG_UNLOCK on the same FID.\nAC:L - The attacker drives both sides: smb2_lock() publishes a granted ksmbd_lock onto conn-\u003elock_list after vfs_lock_file() succeeds for lock element 0, then a later element in the same LockCount\u003e1 array fails (cmd\u003c0, missing SMB2_LOCKFLAG_MASK, or overlap) and walks rollback_list, while a concurrent SMB2 LOCK UNLOCK on ksmbd-io (WQ_PERCPU) kfree()s that object; the race is retryable.\nPR:L - SMB2_LOCK is not in the smb2_check_user_session() pre-auth skip list (only NEGOTIATE/SESSION_SETUP/ECHO); it requires SMB2_SESSION_VALID, smb2_get_ksmbd_tcon() for a tree id, and ksmbd_lookup_fd_slow() after smb2_open(). An ordinary authenticated share user suffices; this is not a pre-auth handshake.\nUI:N - The attacker completes SESSION_SETUP, TREE_CONNECT and CREATE on their own ksmbd TCP connection, then sends the multi-element SMB2 LOCK and concurrent UNLOCK; no victim mount, click, or administrator action is required.\nS:U - The UAF and double-free of ksmbd_lock and struct file_lock occur in the ksmbd-io worker on the host that accepted the SMB session and do not cross a VM, guest-to-host, or IOMMU/DMA boundary.\nC:H - UNLOCK\u0027s kfree(cmp_lock) leaves rollback reading smb_lock-\u003estart, smb_lock-\u003eend, smb_lock-\u003econn and smb_lock-\u003efl from a freed ksmbd_lock; reclaiming that slab or the associated file_lock_cache object with attacker-controlled contents yields an arbitrary kernel read.\nI:H - The same rollback path list_del()s smb_lock-\u003eflist and smb_lock-\u003eclist on the freed object, then locks_free_lock(smb_lock-\u003efl) and kfree(smb_lock) after UNLOCK already freed both, giving a double-free and list_del write primitive for heap corruption and control-flow hijack.\nA:H - Dereferencing the freed ksmbd_lock (including spin_lock on smb_lock-\u003econn-\u003ellist_lock) and double-freeing ksmbd_lock/file_lock oops or panic the ksmbd-io worker; the LOCK/UNLOCK pair can be repeated to crash the host."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:53:30.727Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a1d26dfb32919088e3638dca01068df3c4507433"
        },
        {
          "url": "https://git.kernel.org/stable/c/29f74f0f2e6df3b393b7b66e810136d0c64e3c59"
        }
      ],
      "title": "ksmbd: defer publishing granted locks to prevent UAF/double-free race",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90162",
    "datePublished": "2026-09-17T16:06:53.136Z",
    "dateReserved": "2026-09-11T19:38:34.790Z",
    "dateUpdated": "2026-09-18T17:53:30.727Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

FKIE_CVE-2026-90162

CVE-2026-90162 (GCVE-0-2026-90162)

Tags

Sightings

Nomenclature

Related by attack behaviour