Use-after-free in Linux kernel - CVE-2026-64390

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to a use-after-free in ksmbd byte-range lock handling when processing smb2 lock requests in smb3 multichannel environments. A remote attacker can trigger concurrent lock traversal and removal to cause a denial of service.

The issue occurs because a lock list entry can be removed under a different spinlock than the one protecting the list it belongs to.

Affected software

How to mitigate CVE-2026-64390

External References

• https://git.kernel.org/stable/c/22d38cf75b556c20b039743bdf3654d535b858be
• https://git.kernel.org/stable/c/427faaa52b0b399940c1a88065a5c310d10dad15
• https://git.kernel.org/stable/c/5fecc15a30cb9ebd310f7b52c1ab607edcea78f6
• https://git.kernel.org/stable/c/66eb3643164e5e1029907793926c132f8b5c6148
• https://git.kernel.org/stable/c/c1016dd1d8b2bcd1158bbaabe94a31bb7e7431fb
• https://git.kernel.org/stable/c/ea5c9bf99f626a15cc59f645dc895f2b3f01992e
• https://git.kernel.org/stable/c/fe20d492a69a6f79e637f438072b212e21ed3b78

Related Security Bulletins

• Use-after-free in Linux kernel smb server
• Debian update for linux