Out-of-bounds read in Linux kernel - CVE-2026-98839

Vulnerability identifier: #VU157207

CSH Severity: Low

CVSS v4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98839

CWE-ID: CWE-125

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to potentially disclose sensitive kernel memory.

The vulnerability exists due to an unsigned integer underflow in paste_selection() in drivers/tty/vt/selection.c when a concurrent selection update replaces the selection buffer with a shorter buffer while a paste operation is sleeping. A local user can race a TIOCLINUX (TIOCL_SETSEL) ioctl against the paste operation to make vc_sel.buf_len smaller than the number of bytes already pasted, triggering an out-of-bounds read of up to 4094 bytes that may expose adjacent kernel memory through the terminal line discipline.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-azure (Ubuntu package)
linux-raspi (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-azure-fde-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-gke (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-aws-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-43.43
linux-realtime (Ubuntu package) - update to 7.0.0-43.43.1
linux-oracle (Ubuntu package) - update to 7.0.0-1016.18
linux-aws (Ubuntu package) - update to 7.0.0-1017.18
linux-gcp (Ubuntu package) - update to 7.0.0-1017.19
linux-azure (Ubuntu package) - update to 7.0.0-1020.21
linux-raspi (Ubuntu package) - update to 7.0.0-1023.23
linux-ibm (Ubuntu package) - update to 7.0.0-1018.18
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1016.18~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1017.19~24.04.1
linux-azure-fde-7.0 (Ubuntu package) - update to 7.0.0-1019.19~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1018.18
linux-gke (Ubuntu package) - update to 7.0.0-1010.11
linux-azure-fde (Ubuntu package) - update to 7.0.0-1019.19
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1017.18~24.04.1

• https://git.kernel.org/stable/c/037d7e3ca5c593092f4b0d471eb869a85cbddde0
• https://git.kernel.org/stable/c/39495ef5d6f8019e62d65807f217a7ca8232727a
• https://git.kernel.org/stable/c/619c6d7dd76fff15a9714fbf02ce299b737f01a2

• Out-of-bounds read in Linux kernel tty vt driver
• Ubuntu update for linux, linux-aws, linux-gcp and more
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws-7.0, linux-azure-fde, linux-azure-fde-7.0 and more
• Ubuntu update for linux-raspi