Out-of-bounds write in Linux kernel - CVE-2026-98318

Vulnerability identifier: #VU153707

CSH Severity: Low

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

CVE-ID: CVE-2026-98318

CWE-ID: CWE-787

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to corrupt kernel memory.

The vulnerability exists due to out-of-bounds writes in the SMB client's create_native_symlink() function when processing absolute symlink targets without the expected NT drive prefix. A local user can create a symlink with a crafted absolute target such as "/ab" to corrupt kernel memory.

Exploitation requires write access to a mounted SMB share. The issue occurs when symlinkroot is unset and POSIX paths are not enabled, including with default settings.

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 kernel - update to 7.0 rc3
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/23c240d9509e15f72e4112fc95f0160ab32ec430
• https://git.kernel.org/stable/c/6913ff607c2bc8694193e1fcc40bf16d75f35f16

• Out-of-bounds write in Linux kernel smb client
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more