CVE-2026-90155: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: detach blocked lock requests before freeing A file_lock retained by ksmbd for byte-range lock bookkeeping can still be part of the VFS blocked-request graph. In particular, the VFS can chain a new waiter below an already blocked request through flc_blocked_requests. The ksmbd_file reference count does not cover that graph. Both __ksmbd_close_fd() and the cross-request unlock path free these retained file_lock objects directly. If a dependent waiter is still attached, locks_release_private() hits BUG_ON(!list_empty(&flc->flc_blocked_requests)). The same lifetime mismatch can leave a freed ksmbd_lock reachable through its request-local llist. Detach the file_lock from the blocked-request graph before freeing it in the close, cross-request unlock, and rollback paths. locks_delete_block() also wakes requests chained below the object. Remove llist when a completed lock is published so a globally visible ksmbd_lock no longer points into the submitting worker's stack.

Metrics

EPSS Probability

0.21%

11.0th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= d63528eb0d43c4796c42aad56889dec12cf4e122, < 4e8b69c06bd6583ec11abef4fae50c2c8d5f3679; >= d63528eb0d43c4796c42aad56889dec12cf4e122, < d20d3f6ad8b0b6f4e1bb32cdf7eca251962e8f04; >= d63528eb0d43c4796c42aad56889dec12cf4e122, < d31db79cfaa9fce6649772ad279779473ba8aef9; >= d63528eb0d43c4796c42aad56889dec12cf4e122, < f77d2accafca529e0ea3f979eb6e6cf1dac05c90; >= d63528eb0d43c4796c42aad56889dec12cf4e122, < 514a0b2bc949963497e66cacd433f65dc768a71d; >= d63528eb0d43c4796c42aad56889dec12cf4e122, < 215e8816b1ac25176d911abb8704390413ccee4b
Linux	Linux	5.15

References

Timeline

Published: Sep 17, 2026
Last Modified: Oct 30, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-90155?

In the Linux kernel, the following vulnerability has been resolved: ksmbd: detach blocked lock requests before freeing A file_lock retained by ksmbd for byte-range lock bookkeeping can still be part of the VFS blocked-request graph. In particular, the VFS can chain a new waiter below an already blocked request through flc_blocked_requests. The ksmbd_file reference count does not cover that graph. Both __ksmbd_close_fd() and the cross-request unlock path free these retained file_lock objects directly. If a dependent waiter is still attached, locks_release_private() hits BUG_ON(!list_empty(&flc->flc_blocked_requests)). The same lifetime mismatch can leave a freed ksmbd_lock reachable through its request-local llist. Detach the file_lock from the blocked-request graph before freeing it in the close, cross-request unlock, and rollback paths. locks_delete_block() also wakes requests chained below the object. Remove llist when a completed lock is published so a globally visible ksmbd_lock no longer points into the submitting worker's stack.

How severe is CVE-2026-90155?

Severity scoring for CVE-2026-90155 is pending analysis. The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2026-90155?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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