CVE-2026-64390: Linux Vulnerability (CVSS 8.8)

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: track the connection owning a byte-range lock SMB2_LOCK adds each granted byte-range lock to both the file lock list and the lock list of the connection which handled the request. The final close and durable handle paths, however, remove the connection list entry while holding fp->conn->llist_lock. With SMB3 multichannel, the connection handling the LOCK request can be different from the connection which opened the file. The entry can therefore be removed under a different spinlock from the one protecting the list it belongs to. A concurrent traversal can then access freed struct ksmbd_lock and struct file_lock objects. Record the connection owning each lock's clist entry and hold a reference to it while the entry is linked. Use that connection and its llist_lock for unlock, rollback, close, and durable preserve. Durable reconnect assigns the new connection as the owner when publishing the locks again.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.47%

38.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= f5a544e3bab78142207e0242d22442db85ba1eff, < 22d38cf75b556c20b039743bdf3654d535b858be; >= f5a544e3bab78142207e0242d22442db85ba1eff, < 66eb3643164e5e1029907793926c132f8b5c6148; >= f5a544e3bab78142207e0242d22442db85ba1eff, < ea5c9bf99f626a15cc59f645dc895f2b3f01992e; >= f5a544e3bab78142207e0242d22442db85ba1eff, < fe20d492a69a6f79e637f438072b212e21ed3b78; >= f5a544e3bab78142207e0242d22442db85ba1eff, < 427faaa52b0b399940c1a88065a5c310d10dad15; >= f5a544e3bab78142207e0242d22442db85ba1eff, < 5fecc15a30cb9ebd310f7b52c1ab607edcea78f6; >= f5a544e3bab78142207e0242d22442db85ba1eff, < c1016dd1d8b2bcd1158bbaabe94a31bb7e7431fb
Linux	Linux	5.15

References

Timeline

Published: Jul 25, 2026
Last Modified: Aug 11, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-64390?

In the Linux kernel, the following vulnerability has been resolved: ksmbd: track the connection owning a byte-range lock SMB2_LOCK adds each granted byte-range lock to both the file lock list and the lock list of the connection which handled the request. The final close and durable handle paths, however, remove the connection list entry while holding fp->conn->llist_lock. With SMB3 multichannel, the connection handling the LOCK request can be different from the connection which opened the file. The entry can therefore be removed under a different spinlock from the one protecting the list it belongs to. A concurrent traversal can then access freed struct ksmbd_lock and struct file_lock objects. Record the connection owning each lock's clist entry and hold a reference to it while the entry is linked. Use that connection and its llist_lock for unlock, rollback, close, and durable preserve. Durable reconnect assigns the new connection as the owner when publishing the locks again.

How severe is CVE-2026-64390?

CVE-2026-64390 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.

How do I fix CVE-2026-64390?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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