Improper locking in Linux kernel - CVE-2026-89956

Vulnerability identifier: #VU150338

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-2026-89956

CWE-ID: CWE-667

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause kernel memory corruption or a use-after-free condition.

The vulnerability exists due to improper locking in the s390 VFIO AP mediated-device list handling when concurrently creating, removing, or looking up mediated devices. A local user can concurrently manipulate mediated devices to cause kernel memory corruption or a use-after-free condition.

Linux kernel
Debian Linux
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)
linux (Debian 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
linux (Debian package) - update to 6.12.113-1

• https://git.kernel.org/stable/c/0fd74477d05743d4cd9b25a3b667daa278d53b93
• https://git.kernel.org/stable/c/647916988272fe5ecb4bb30cd02b51af9960618a
• https://git.kernel.org/stable/c/7fa61c29850d05e40ca9ed41bfdf57673023f581

• Improper locking in Linux kernel s390 crypto driver
• Debian update for linux
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more