CVE-2026-90164: smb/server: abort initialization when proc setup fails

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-17 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: smb/server: abort initialization when proc setup fails ksmbd_server_init() calls ksmbd_proc_init() before creating the remaining proc entries and server subsystems. ksmbd_proc_init() tears down partial state on a procfs or percpu_counter allocation failure, but returns void, so ksmbd_server_init() continues as if the counters were usable. Once userspace starts the server, server_ctrl_handle_init() calls ksmbd_proc_reset(), which reaches percpu_counter_set() with a NULL per-CPU counters pointer on SMP systems. The later ksmbd_proc_create() calls also receive a NULL parent and may create entries in the /proc root; ksmbd_proc_cleanup() cannot remove those entries because ksmbd_proc_fs is NULL.

Affected products

Linux kernel: 7.0 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

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