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CVE-2026-97556

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

Products / packages Linux

Published

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Severity and exploitation

Not in CISA KEVNo CVSS score

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 21:40:35 UTC

Severity

unknown

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

A reference leak vulnerability in the Linux kernel's SMB client may cause a crash due to busy inodes on unmount. The issue affects Linux kernel versions 5.15.128 to 5.15.224, 6.1.47 to 6.1.189, 6.4.12, and 6.5. The vulnerability occurs when cifs_sb_tlink() fails in setups with the '-o multiuser' option.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

Linux · Linux

Linux

11 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

b99f490ea87ebcca3a429fd8837067feb56a4c7c → before f1fd8a84181b3af03c508e0b02b4877945dd070a

git versions

5ee28bcfbaacf289eb25c662a2862542ea6ce6a7 → before 55c5f095d4df14271b238f826e1392fda7b6e60e

git versions

e8f5f849ffce24490eb9449e98312b66c0dba76f → before e9c5bcc88b8337157e480c85a6d2f326bc265012

git versions

e8f5f849ffce24490eb9449e98312b66c0dba76f → before 9ec991e148368e3207e98134c509a625097f7693

git versions

e8f5f849ffce24490eb9449e98312b66c0dba76f → before dd03fd658ea59821505e0e643b6b7cbdf51c4e1d

git versions

e8f5f849ffce24490eb9449e98312b66c0dba76f → before 1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd

git versions

e8f5f849ffce24490eb9449e98312b66c0dba76f → before 23b26f4408ac3f35a482d2e5cf6fc865d4201b71

git versions

6b67a6d2e50634fe127e656147c81915955e9f5e

git versions

5.15.128 → before 5.15.224

semver versions

6.1.47 → before 6.1.189

semver versions

6.4.12 → before 6.5

semver versions

unaffected

unknown

Other versions: unaffected

Linux · Linux

Linux

9 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

6.5

unaffected

0 → before 6.5

semver versions

5.15.224 → through 5.15.*

semver versions

6.1.189 → through 6.1.*

semver versions

6.6.158 → through 6.6.*

semver versions

6.12.111 → through 6.12.*

semver versions

6.18.53 → through 6.18.*

semver versions

7.2.7 → through 7.2.*

semver versions

7.3 → through *

original_commit_for_fix versions

unknown

Other versions: affected

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

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

7 sources
git.kernel.org/stable/c/f1fd8a84181b3af03c508e0b02b4877945dd070a
Source referenceLinux
git.kernel.org/stable/c/55c5f095d4df14271b238f826e1392fda7b6e60e
Source referenceLinux
git.kernel.org/stable/c/e9c5bcc88b8337157e480c85a6d2f326bc265012
Source referenceLinux
git.kernel.org/stable/c/9ec991e148368e3207e98134c509a625097f7693
Source referenceLinux
git.kernel.org/stable/c/dd03fd658ea59821505e0e643b6b7cbdf51c4e1d
Source referenceLinux
git.kernel.org/stable/c/1d1b0f1d812a4011a57bc6c70492c34a2e46c6dd
Source referenceLinux
View 1 more references
git.kernel.org/stable/c/23b26f4408ac3f35a482d2e5cf6fc865d4201b71
Source referenceLinux

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification · not supplied
Additional publishers · not supplied

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-97556

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

Linux · platform conditions

Any condition may hold

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.15.128

Before: 5.15.224

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 6.1.47

Before: 6.1.189

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 6.5

Before: 6.6.158

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 6.5

Before: 6.12.111

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 6.5

Before: 6.18.53

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 6.5

Before: 7.2.7

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 6.5

Before: 7.3

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 6.4.12

Applicability preview
[
  {
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.15.128",
            "versionEndExcluding": "5.15.224"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "6.1.47",
            "versionEndExcluding": "6.1.189"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "6.5",
            "versionEndExcluding": "6.6.158"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "6.5",
            "versionEndExcluding": "6.12.111"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "6.5",
            "versionEndExcluding": "6.18.53"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "6.5",
            "versionEndExcluding": "7.2.7"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "6.5",
            "versionEndExcluding": "7.3"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "6.4.12"
          }
        ]
      }
    ]
  }
]
Contributing organizations · 1
Linux

Assigning organization

2026-10-30

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.