CVE-2026-64392: ksmbd: use opener credentials for delete-on-close

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-25 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for delete-on-close Delete-on-close can be completed by deferred or durable handle teardown, where no request work is available. Both the base-file unlink and the ADS xattr removal consequently run with the ksmbd worker credentials and can bypass filesystem permission checks. Run both operations with the credentials captured in struct file when the handle was opened. This preserves the authenticated user's fsuid, fsgid, supplementary groups and capability restrictions at final close.

Affected products

Linux kernel: from 5.15 before 6.6.145; from 6.7 before 6.12.96; from 6.13 before 6.18.39; from 6.19 before 7.1.4 — fixed in 6.6.145, 6.12.96, 6.18.39, 7.1.4
Linux: 5.15 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 6.6.145, 6.12.96, 6.18.39, 7.1.4; Linux 7.2. Check the vendor advisory for mitigations.

References

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