Improper locking in Linux kernel - CVE-2026-90338

Vulnerability identifier: #VU151143

CSH Severity: Low

CVSS v4: 2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-90338

CWE-ID: CWE-667

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper locking in pl011_console_write_atomic() when processing atomic console writes. A local user can trigger an atomic-context printk while the common-clock enable lock is contended to cause a denial of service.

The condition was reproduced on PREEMPT_RT systems with clock-backed pl011 consoles and may also occur from NMI context.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

Install security update from vendor's repository.

linux (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17

• https://git.kernel.org/stable/c/2ad24c1d0b939d814a3020f96a667ac2d0394289
• https://git.kernel.org/stable/c/5b77848423f4a5a362dcc3caedcdc1a75d0758c3
• https://git.kernel.org/stable/c/c0e8cfef754645856374e82c8effd54b7d82002b

• Improper locking in Linux kernel tty serial driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more