Use of Uninitialized Variable in Linux kernel - CVE-2026-90272

Vulnerability identifier: #VU151216

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-90272

CWE-ID: CWE-457

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to disclose uninitialized kernel memory.

The vulnerability exists due to use of uninitialized memory in the arm_pmuv3 BRBE branch stack handling when collecting branch records with PERF_SAMPLE_BRANCH_HW_INDEX. A local user can request branch records containing an unset hw_id value to disclose uninitialized kernel memory.

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/57b72442c1672963fd51ab441ca1b71f6dc79b66
• https://git.kernel.org/stable/c/7c3b63386c27bed8d59a4b4c283d02860420eb0a
• https://git.kernel.org/stable/c/988e11b69ef9d4034e19c64407030fa948580c3d

• Use of Uninitialized Variable in Linux kernel perf driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more