« Back to list

CVE-2026-97556

Status: ReceivedUnscored—

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:

Read full descriptionShow less

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.

Technical details traces, logs and code from the original report
  BUG: Dentry ... still in use (1) [unmount of cifs cifs]
  VFS: Busy inodes after unmount of cifs (cifs)

CVSS

NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Linux — Linux KernelAI

References

Raw JSON (NVD)

Show
{
  "id": "CVE-2026-97556",
  "cveTags": [],
  "metrics": {},
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5ee28bcfbaacf289eb25c662a2862542ea6ce6a7",
              "lessThan": "55c5f095d4df14271b238f826e1392fda7b6e60e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "lessThan": "e9c5bcc88b8337157e480c85a6d2f326bc265012",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "lessThan": "9ec991e148368e3207e98134c509a625097f7693",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "lessThan": "dd03fd658ea59821505e0e643b6b7cbdf51c4e1d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "lessThan": "1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e8f5f849ffce24490eb9449e98312b66c0dba76f",
              "lessThan": "23b26f4408ac3f35a482d2e5cf6fc865d4201b71",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b99f490ea87ebcca3a429fd8837067feb56a4c7c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6b67a6d2e50634fe127e656147c81915955e9f5e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6.1.47",
              "lessThan": "6.1.189",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "5.15.128",
              "lessThan": "5.16",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "6.4.12",
              "lessThan": "6.5",
              "versionType": "semver"
            }
          ],
          "programFiles": [
            "fs/smb/client/file.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.5",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/smb/client/file.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-25T11:17:06.077",
  "references": [
    {
      "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/55c5f095d4df14271b238f826e1392fda7b6e60e",
      "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",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/e9c5bcc88b8337157e480c85a6d2f326bc265012",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "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."
    }
  ],
  "lastModified": "2026-10-03T11:18:03.327",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}