SECUFOCUSNOW
Home›CVE index›CVE-2026-64401
Review reviewHigh

CVE-2026-64401

Linux

In the Linux kernel, the following vulnerability has been resolved: smb: client: resolve SWN tcon from live registrations cifs_swn_notify() looks up a witness registration by id under cifs_swnreg_idr_mutex, drops the mutex, and then uses the registration's cached tcon pointer. That pointer is not a lifetime reference, and it is not a stable representative once cifs_get_swn_reg() lets multiple tcons for the same net/share name share one registration id. A same-share second mount can keep the cifs_swn_reg alive after the first tcon unregisters and is freed. The registration then still points...

CVSS
7.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.25
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.8

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: smb: client: resolve SWN tcon from live registrations cifs_swn_notify() looks up a witness registration by id under cifs_swnreg_idr_mutex, drops the mutex, and then uses the registration's cached tcon pointer. That pointer is not a lifetime reference, and it is not a stable representative once cifs_get_swn_reg() lets multiple tcons for the same net/share name share one registration id. A same-share second mount can keep the cifs_swn_reg alive after the first tcon unregisters and is freed. The registration then still points...

Affected product and versions

Product
Linux
Affected versions
>= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 < 51d18db392e5386a7bb9e816d611f14e600cca3c, >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 < aa3c0cab4b28c5007ec570c63e1d6ad6943ed0fd, >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 < 945b4a4a54497db1dcb2f20ef801a84e884dac21, >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 < 91b8a58c6ac15c7db6518f696389933282f88da7, >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 < 0700f946659d0ab2352ec8a9b1c6fc74b13a27d7, >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 < ec457f9afe5ae9538bdcd58fd4cb442b9787e183, >= 5.11
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
Not available