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Review reviewHigh

CVE-2026-64396

Linux

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation When a blocking byte-range lock request is deferred in the FILE_LOCK_DEFERRED path, ksmbd registers the asynchronous work into the connection's async_requests list via setup_async_work(). The cancel callback smb2_remove_blocked_lock() holds a reference to the flock. If the lock waiter is subsequently woken up but the work state is no longer KSMBD_WORK_ACTIVE (e.g., due to a concurrent cancellation), the cleanup path calls locks_free_lock(flock) witho...

CVSS
8.8
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 8.8

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation When a blocking byte-range lock request is deferred in the FILE_LOCK_DEFERRED path, ksmbd registers the asynchronous work into the connection's async_requests list via setup_async_work(). The cancel callback smb2_remove_blocked_lock() holds a reference to the flock. If the lock waiter is subsequently woken up but the work state is no longer KSMBD_WORK_ACTIVE (e.g., due to a concurrent cancellation), the cleanup path calls locks_free_lock(flock) witho...

Affected product and versions

Product
Linux
Affected versions
>= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 367c42a611fe488b7b03f1f6737f4dee0e8b20a2, >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 7703fd9aba1f2483c8e55f9ff73b7663e0761ed9, >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 463bbd79698513af4dad50fe1c573825f297ca2e, >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 5aa1cb01155f96824003baf7997cdf1f150caba3, >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 5c75275c0fc9a2deb0d8f5604edcb16f288171c8, >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < d20d1c8ba5765d1d12eefc0aee6385ab3f240e1e, >= 5.15
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:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
Not available
CVE-2026-64396 — Linux | SECUFOCUS NOW