Vulnerability-Lookup

FKIE_CVE-2026-89636

Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-09-14 13:19

Severity

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

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: clear ce->tgthint in free_tgts() When free_tgts() frees all structures in ce->tlist, ce->tgthint is left pointing to one of the freed cache_dfs_tgt structures. If ce->tgthint is not reset before it is used later, it results in a use-after-free. Set ce->tgthint to NULL in free_tgts() after the elements are freed to reflect that no elements remain.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/14f60e959b5ac813715ff72e127beb3584ddabf6
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/3ff9462bb7a06d8d32a1dc02d39580b078ec9e55
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/5baab40404a9393bcc0b7b8f1950bf2c307e0984
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7507bd1885643d0461a6017767492450af1ce2a3
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/9ab46a13798a61d9d020b01d4e57efdabe6624fa
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/b1b741cf8e7ce1b91d937e23decd3d3358748700

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/dfs_cache.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "14f60e959b5ac813715ff72e127beb3584ddabf6",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "3ff9462bb7a06d8d32a1dc02d39580b078ec9e55",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "7507bd1885643d0461a6017767492450af1ce2a3",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "9ab46a13798a61d9d020b01d4e57efdabe6624fa",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "5baab40404a9393bcc0b7b8f1950bf2c307e0984",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "b1b741cf8e7ce1b91d937e23decd3d3358748700",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/dfs_cache.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.0"
            },
            {
              "lessThan": "5.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "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\nsmb: client: clear ce-\u003etgthint in free_tgts()\n\nWhen free_tgts() frees all structures in ce-\u003etlist, ce-\u003etgthint\nis left pointing to one of the freed cache_dfs_tgt structures.\n\nIf ce-\u003etgthint is not reset before it is used later, it results\nin a use-after-free.\n\nSet ce-\u003etgthint to NULL in free_tgts() after the elements are\nfreed to reflect that no elements remain."
    }
  ],
  "id": "CVE-2026-89636",
  "lastModified": "2026-09-14T13:19:16.797",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-11T20:19:49.243",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/14f60e959b5ac813715ff72e127beb3584ddabf6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3ff9462bb7a06d8d32a1dc02d39580b078ec9e55"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5baab40404a9393bcc0b7b8f1950bf2c307e0984"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7507bd1885643d0461a6017767492450af1ce2a3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9ab46a13798a61d9d020b01d4e57efdabe6624fa"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b1b741cf8e7ce1b91d937e23decd3d3358748700"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-89636 (GCVE-0-2026-89636)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-14 12:01

Title

smb: client: clear ce->tgthint in free_tgts()

Summary

Severity

9.8 (Critical)


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

Assigner

Linux mitre root

References

6 references

URL	Tags
https://git.kernel.org/stable/c/14f60e959b5ac8137…
https://git.kernel.org/stable/c/3ff9462bb7a06d8d3…
https://git.kernel.org/stable/c/7507bd1885643d046…
https://git.kernel.org/stable/c/9ab46a13798a61d9d…
https://git.kernel.org/stable/c/5baab40404a9393bc…
https://git.kernel.org/stable/c/b1b741cf8e7ce1b91…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 54be1f6c1c37498bba557049df646cc239fa37e3 , < 14f60e959b5ac813715ff72e127beb3584ddabf6 (git) Affected: 54be1f6c1c37498bba557049df646cc239fa37e3 , < 3ff9462bb7a06d8d32a1dc02d39580b078ec9e55 (git) Affected: 54be1f6c1c37498bba557049df646cc239fa37e3 , < 7507bd1885643d0461a6017767492450af1ce2a3 (git) Affected: 54be1f6c1c37498bba557049df646cc239fa37e3 , < 9ab46a13798a61d9d020b01d4e57efdabe6624fa (git) Affected: 54be1f6c1c37498bba557049df646cc239fa37e3 , < 5baab40404a9393bcc0b7b8f1950bf2c307e0984 (git) Affected: 54be1f6c1c37498bba557049df646cc239fa37e3 , < b1b741cf8e7ce1b91d937e23decd3d3358748700 (git)
Linux	Linux	Affected: 5.0 Unaffected: 0 , < 5.0 (semver) Unaffected: 6.1.188 , ≤ 6.1.* (semver) Unaffected: 6.6.157 , ≤ 6.6.* (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 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/client/dfs_cache.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "14f60e959b5ac813715ff72e127beb3584ddabf6",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "3ff9462bb7a06d8d32a1dc02d39580b078ec9e55",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "7507bd1885643d0461a6017767492450af1ce2a3",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "9ab46a13798a61d9d020b01d4e57efdabe6624fa",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "5baab40404a9393bcc0b7b8f1950bf2c307e0984",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            },
            {
              "lessThan": "b1b741cf8e7ce1b91d937e23decd3d3358748700",
              "status": "affected",
              "version": "54be1f6c1c37498bba557049df646cc239fa37e3",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/dfs_cache.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.0"
            },
            {
              "lessThan": "5.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "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": "6.1.188",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.109",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: clear ce-\u003etgthint in free_tgts()\n\nWhen free_tgts() frees all structures in ce-\u003etlist, ce-\u003etgthint\nis left pointing to one of the freed cache_dfs_tgt structures.\n\nIf ce-\u003etgthint is not reset before it is used later, it results\nin a use-after-free.\n\nSet ce-\u003etgthint to NULL in free_tgts() after the elements are\nfreed to reflect that no elements remain."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The dangling ce-\u003etgthint 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 \u2192 cache_refresh_path \u2192 update_cache_entry_locked \u2192 free_tgts). A malicious, compromised, or MITM\u0027d 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\u0027d 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-\u003ename). 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 \u2192 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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-14T12:01:41.762Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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-\u003etgthint in free_tgts()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89636",
    "datePublished": "2026-09-11T19:45:30.283Z",
    "dateReserved": "2026-09-11T19:38:34.739Z",
    "dateUpdated": "2026-09-14T12:01:41.762Z",
    "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.

Detection rules are retrieved from Rulezet.

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

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