NULL pointer dereference in Linux kernel - CVE-2026-74738

Vulnerability identifier: #VU145990

CSH Severity: Low

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-74738

CWE-ID: CWE-476

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local attacker to cause a denial of service.

The vulnerability exists due to a NULL function pointer dereference in regmap_sdw_mbq_poll_busy() in the regmap sdw-mbq component when handling devices that answer COMMAND_IGNORED and no readable_reg callback is set. A local attacker can trigger the code path to cause a denial of service.

The issue occurs because a missing readable_reg callback is treated incorrectly during Function Busy polling after an -ENODATA condition.

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/00268f9452d2a0d660aa9c1bb0ca07a994af6a4f
• https://git.kernel.org/stable/c/5bd8e897ecf558507142f4553e4526adfc1d6482
• https://git.kernel.org/stable/c/6cf600b276a55a6481462830607a611f32e737c0

• NULL pointer dereference in Linux kernel base regmap driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more