Use of Uninitialized Variable in Linux kernel - CVE-2026-64082

Vulnerability identifier: #VU138563

CSH Severity: Low

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

CVE-ID: CVE-2026-64082

CWE-ID: CWE-457

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to corrupt register state and disclose kernel stack contents.

The vulnerability exists due to use of uninitialized stack data in compat_riscv_gpr_set() and compat_restore_sigcontext() when handling failed user memory copies. A local user can provide crafted user-supplied register or signal context data that triggers a copy failure to corrupt register state and disclose kernel stack contents.

The issue affects the RISC-V compatibility signal and ptrace handling paths.

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• https://git.kernel.org/stable/c/6ebcbb53fc9bc30843054ed99fd60b8e542628f4
• https://git.kernel.org/stable/c/9e020156833f1ad0d425a1e3d85b65639f1c1c50

• Use of Uninitialized Variable in Linux kernel riscv kernel
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia