Always-Incorrect Control Flow Implementation in Linux kernel - CVE-2026-98883

Vulnerability identifier: #VU157633

CSH Severity: Low

CVSS v4: 0 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98883

CWE-ID: CWE-670

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local privileged user to trigger an erroneous kernel warning during initialization of an affected serial port.

The vulnerability exists due to improper handling of the UPIO_AU UART I/O type in set_io_from_upio() when probing affected 8250 serial ports on MIPS Alchemy systems. A local privileged user can trigger serial-port initialization, if able to initiate probing, to generate an erroneous unsupported-UART warning despite the port parameters already being configured.

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/49fa670efdfdd27e29145cbd2beef065c08717ef
• https://git.kernel.org/stable/c/9f67997353caa29c6a080789a1fb6e01fb50c118

• Always-Incorrect Control Flow Implementation in Linux kernel serial 8250 driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more