CVE-2026-89635 Linux Kernel ksmbd - Use After Free

Linux kernel ksmbd contains a use-after-free vulnerability caused by rebinding oplocks of all detached durable handles on an inode to a reconnecting session instead of only the file's own, letting authenticated attackers cause kernel memory corruption during durable reconnects, exploit requires multiple sessions with durable handles on the same file.

CVSS base score 9.8 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.55% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Use After Free
Impact
Denial Of Service, Privilege Escalation
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
11 September 2026
Updated
15 October 2026

Vendor fix

Update to the latest Linux kernel version containing the ksmbd fix for durable reconnect oplock rebinding.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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