kernel: vt: selection: Fix unsigned underflow and slab-out-of-bounds read in paste_selection() (CVE-2026-98839)

Overview

A flaw was found in the Linux kernel's virtual terminal selection subsystem. When pasting console selections, a race condition can occur if another process concurrently replaces the selection buffer with shorter content while the operation is temporarily paused. This situation causes an integer underflow that leads to an out-of-bounds memory read. A local user can exploit this vulnerability to cause a system crash, resulting in a Denial of Service (DoS), or potentially expose sensitive kernel memory.

Vendor advisories

• Red Hat VEX · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-23 · vex

kernel: vt: selection: Fix unsigned underflow and slab-out-of-bounds read in paste_selection() — rated Moderate by Red Hat. Released 2026-10-18, updated 2026-10-23.

Affected:

• Red Hat Enterprise Linux 10
• Red Hat Enterprise Linux 8
• Red Hat Enterprise Linux 9
• Red Hat OpenShift Container Platform 4

No fix planned:

• Red Hat Enterprise Linux 10
• Red Hat Enterprise Linux 8
• Red Hat Enterprise Linux 9
• Red Hat OpenShift Container Platform 4

Not affected:

• Red Hat Enterprise Linux 6
• Red Hat Enterprise Linux 7

Remediation

Fix deferred