Improper update of reference count in Linux kernel - CVE-2026-74721

Vulnerability identifier: #VU144602

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-2026-74721

CWE-ID: CWE-911

Exploitation vector: Local access

Exploit availability: No public exploit available

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

The vulnerability exists due to incorrect reference count management in amdxdna_insert_pages() when handling page-insertion errors during memory mapping. A local user can trigger page-insertion failures to cause a denial of service.

The issue arises because VMA close handling can occur before the mmap operation has returned, and the VMA may later be torn down again, leading to a reference count underflow.

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/1501e4d07c6fee0d50531a0d1cb2be01a63e6e75
• https://git.kernel.org/stable/c/8d51e0fd3e698919d2adeff71936377f0c0d4aa0

• Improper update of reference count in Linux kernel accel amdxdna driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more