CVE-2026-89630 Linux Kernel smb client - Broken Access Control

Linux kernel smb client contains a broken access control vulnerability caused by incorrect data_offset bound check in is_valid_oplock_break(), letting attackers bypass read overflow protections, exploit requires crafted SMB messages.

CVSS base score 9.1 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.54% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Broken Access Control
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Published
11 September 2026
Updated
15 October 2026

Vendor fix

Update to the latest Linux kernel version containing the fix for is_valid_oplock_break() data_offset bound restoration.

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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