Vulnerability-Lookup

FKIE_CVE-2026-97556

Vulnerability from fkie_nvd - Published: 2026-09-25 11:17 - Updated: 2026-09-25 11:17

Severity

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: avoid leaking refcount when cifs_sb_tlink() fails cifs_oplock_break() takes over the reference that cifs_queue_oplock_break() acquired when it queued the work, and drops it with _cifsFileInfo_put() once the break has been processed. Only in setups with "-o multiuser", cifs_sb_tlink() may fail, at which point cifs_oplock_break() returns without putting the file reference, mirroring the reference leak we already fixed in the companion patch to cifs_queue_oplock_break(). This would trigger a crash due to busy inodes on the next unmount: BUG: Dentry ... still in use (1) [unmount of cifs cifs] VFS: Busy inodes after unmount of cifs (cifs) Drop the reference on that path as well. Doing so before the out label mirrors the normal path, which also puts the reference before cifs_done_oplock_break(). Found by Sashiko code review. The failure path was not exercised at runtime.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/23b26f4408ac3f35a482d2e5cf6fc865d4201b71
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/9ec991e148368e3207e98134c509a625097f7693
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/dd03fd658ea59821505e0e643b6b7cbdf51c4e1d

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9ec991e148368e3207e98134c509a625097f7693",
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "versionType": "git"
            },
            {
              "lessThan": "dd03fd658ea59821505e0e643b6b7cbdf51c4e1d",
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "versionType": "git"
            },
            {
              "lessThan": "1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd",
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "versionType": "git"
            },
            {
              "lessThan": "23b26f4408ac3f35a482d2e5cf6fc865d4201b71",
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b99f490ea87ebcca3a429fd8837067feb56a4c7c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5ee28bcfbaacf289eb25c662a2862542ea6ce6a7",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6b67a6d2e50634fe127e656147c81915955e9f5e",
              "versionType": "git"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.128",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.47",
              "versionType": "semver"
            },
            {
              "lessThan": "6.5",
              "status": "affected",
              "version": "6.4.12",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
              "lessThan": "6.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc3",
              "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: avoid leaking refcount when cifs_sb_tlink() fails\n\ncifs_oplock_break() takes over the reference that\ncifs_queue_oplock_break() acquired when it queued the work, and drops it\nwith _cifsFileInfo_put() once the break has been processed.\n\nOnly in setups with \"-o multiuser\", cifs_sb_tlink() may fail, at which\npoint cifs_oplock_break() returns without putting the file reference,\nmirroring the reference leak we already fixed in the companion patch to\ncifs_queue_oplock_break().\n\nThis would trigger a crash due to busy inodes on the next unmount:\n\n  BUG: Dentry ... still in use (1) [unmount of cifs cifs]\n  VFS: Busy inodes after unmount of cifs (cifs)\n\nDrop the reference on that path as well. Doing so before the out label\nmirrors the normal path, which also puts the reference before\ncifs_done_oplock_break().\n\nFound by Sashiko code review. The failure path was not exercised at\nruntime."
    }
  ],
  "id": "CVE-2026-97556",
  "lastModified": "2026-09-25T11:17:06.077",
  "metrics": {},
  "published": "2026-09-25T11:17:06.077",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/23b26f4408ac3f35a482d2e5cf6fc865d4201b71"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9ec991e148368e3207e98134c509a625097f7693"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/dd03fd658ea59821505e0e643b6b7cbdf51c4e1d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-97556 (GCVE-0-2026-97556)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:21 – Updated: 2026-09-25 10:21

Title

smb: client: avoid leaking refcount when cifs_sb_tlink() fails

Summary

Severity

No CVSS data available.

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/9ec991e148368e320…
https://git.kernel.org/stable/c/dd03fd658ea598215…
https://git.kernel.org/stable/c/1d1b0f1d812a4011a…
https://git.kernel.org/stable/c/23b26f4408ac3f35a…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: e8f5f849ffce24490eb9449e98312b66c0dba76f , < 9ec991e148368e3207e98134c509a625097f7693 (git) Affected: e8f5f849ffce24490eb9449e98312b66c0dba76f , < dd03fd658ea59821505e0e643b6b7cbdf51c4e1d (git) Affected: e8f5f849ffce24490eb9449e98312b66c0dba76f , < 1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd (git) Affected: e8f5f849ffce24490eb9449e98312b66c0dba76f , < 23b26f4408ac3f35a482d2e5cf6fc865d4201b71 (git) Affected: b99f490ea87ebcca3a429fd8837067feb56a4c7c (git) Affected: 5ee28bcfbaacf289eb25c662a2862542ea6ce6a7 (git) Affected: 6b67a6d2e50634fe127e656147c81915955e9f5e (git) Affected: 5.15.128 , < 5.16 (semver) Affected: 6.1.47 , < 6.2 (semver) Affected: 6.4.12 , < 6.5 (semver)
Linux	Linux	Affected: 6.5 Unaffected: 0 , < 6.5 (semver) Unaffected: 6.12.111 , ≤ 6.12.* (semver) Unaffected: 6.18.53 , ≤ 6.18.* (semver) Unaffected: 7.2.7 , ≤ 7.2.* (semver) Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9ec991e148368e3207e98134c509a625097f7693",
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "versionType": "git"
            },
            {
              "lessThan": "dd03fd658ea59821505e0e643b6b7cbdf51c4e1d",
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "versionType": "git"
            },
            {
              "lessThan": "1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd",
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "versionType": "git"
            },
            {
              "lessThan": "23b26f4408ac3f35a482d2e5cf6fc865d4201b71",
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b99f490ea87ebcca3a429fd8837067feb56a4c7c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5ee28bcfbaacf289eb25c662a2862542ea6ce6a7",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6b67a6d2e50634fe127e656147c81915955e9f5e",
              "versionType": "git"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.128",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.47",
              "versionType": "semver"
            },
            {
              "lessThan": "6.5",
              "status": "affected",
              "version": "6.4.12",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
              "lessThan": "6.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.7",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc3",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.15.128",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.1.47",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.4.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: avoid leaking refcount when cifs_sb_tlink() fails\n\ncifs_oplock_break() takes over the reference that\ncifs_queue_oplock_break() acquired when it queued the work, and drops it\nwith _cifsFileInfo_put() once the break has been processed.\n\nOnly in setups with \"-o multiuser\", cifs_sb_tlink() may fail, at which\npoint cifs_oplock_break() returns without putting the file reference,\nmirroring the reference leak we already fixed in the companion patch to\ncifs_queue_oplock_break().\n\nThis would trigger a crash due to busy inodes on the next unmount:\n\n  BUG: Dentry ... still in use (1) [unmount of cifs cifs]\n  VFS: Busy inodes after unmount of cifs (cifs)\n\nDrop the reference on that path as well. Doing so before the out label\nmirrors the normal path, which also puts the reference before\ncifs_done_oplock_break().\n\nFound by Sashiko code review. The failure path was not exercised at\nruntime."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T10:21:47.078Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9ec991e148368e3207e98134c509a625097f7693"
        },
        {
          "url": "https://git.kernel.org/stable/c/dd03fd658ea59821505e0e643b6b7cbdf51c4e1d"
        },
        {
          "url": "https://git.kernel.org/stable/c/1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd"
        },
        {
          "url": "https://git.kernel.org/stable/c/23b26f4408ac3f35a482d2e5cf6fc865d4201b71"
        }
      ],
      "title": "smb: client: avoid leaking refcount when cifs_sb_tlink() fails",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97556",
    "datePublished": "2026-09-25T10:21:47.078Z",
    "dateReserved": "2026-09-24T16:01:01.154Z",
    "dateUpdated": "2026-09-25T10:21:47.078Z",
    "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.
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FKIE_CVE-2026-97556

CVE-2026-97556 (GCVE-0-2026-97556)

Tags

Sightings

Nomenclature

Related by attack behaviour