Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel - CVE-2026-90009
Published: September 16, 2026
Vulnerability identifier: #VU150278
CSH Severity: Low
CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-90009
CWE-ID: CWE-367
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service and compromise confidentiality and integrity.
The vulnerability exists due to a time-of-check to time-of-use race condition in scsi_bsg_uring_cmd() when processing io_uring passthrough commands from a shared memory-mapped submission queue entry. A local user can modify the request length after validation to overflow scmd->cmnd during copy_from_user() and cause a denial of service and compromise confidentiality and integrity.
Affected software
Linux kernel
How to mitigate CVE-2026-90009
Install security update from vendor's repository.