Improper locking in Linux kernel - CVE-2026-64428
Published: July 27, 2026
Vulnerability identifier: #VU139539
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64428
CWE-ID: CWE-667
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper lock type selection in the sch irq startup path when starting up a requested irq on PREEMPT_RT systems. A local user can request a threaded irq that reaches sch_irq_unmask() and sch_irq_mask_unmask() to cause a denial of service.
The issue occurs because the path is not sleepable, but a regular spinlock_t becomes a sleeping lock on PREEMPT_RT.
Affected software
Linux kernel
Debian Linux
linux (Debian package)
Debian Linux
linux (Debian package)
How to mitigate CVE-2026-64428
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
linux (Debian package) - update to 6.12.100-1
linux (Debian package) - update to 6.12.100-1
External References
- https://git.kernel.org/stable/c/286533cb14a3c8a8bd39ff64ea2fc8e1aa0f638b
- https://git.kernel.org/stable/c/3b1aa05ec27eeccc889ecaa3f2d9baa9f453e50d
- https://git.kernel.org/stable/c/41cad91a09d69e8fff4e936db29b1054b4e9f9f7
- https://git.kernel.org/stable/c/4508366ab7dd0c2917a51a9c2e23cc1b9d35157a
- https://git.kernel.org/stable/c/4f03a15cc73c83740fc355ee22b336492d17b4da
- https://git.kernel.org/stable/c/7a550256d68bbdfa0903ab1c4595c04a6815493a
- https://git.kernel.org/stable/c/a235cec779bb39ec8f961a935b28a2ce278c6c64