CVE-2025-71189: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-71189 is a memory leak (resource leak) vulnerability in the Linux kernel's dmaengine: dw: dmamux driver. When a DMA route allocation fails at a late stage, the driver does not properly release the reference taken to the DMA master Open Firmware (OF) node, resulting in a kernel memory leak. The vulnerability affects Linux kernel versions from 5.19.1 through multiple stable branches up to 6.18.x, as well as 6.19 release candidates. It was published on January 31, 2026, and carries a CVSS v3.1 base score of 5.5 (Medium) (Red Hat CVE, Feedly).

The root cause is classified as CWE-401 (Missing Release of Memory after Effective Lifetime). In the dw_dmamux driver, when a route allocation fails after a reference to the DMA master OF node has already been taken, the error-handling code path does not call the corresponding of_node_put() to decrement the reference count. This results in the OF node reference being permanently leaked. Exploitation requires local access with low privileges to trigger repeated route allocation failures, causing incremental memory exhaustion in the kernel (Red Hat CVE, Kernel Patches).

Successful exploitation leads to a denial-of-service condition through gradual kernel memory exhaustion. An attacker with local, low-privileged access can repeatedly trigger DMA route allocation failures, causing the kernel to accumulate unreleased OF node references over time. There is no impact on data confidentiality or integrity; the vulnerability is limited to system availability (Red Hat CVE, Feedly).

Patches have been applied to multiple Linux kernel stable branches. Administrators should upgrade to the following fixed versions or later:

• 6.1.162 or later (for kernel versions 5.19.1–6.1.x)
• 6.6.122 or later (for kernel versions 6.2–6.6.x)
• 6.12.67 or later (for kernel versions 6.7–6.12.x)
• 6.18.7 or later (for kernel versions 6.13–6.18.x)
• 6.19-rc6 or later (for 6.19 release candidates)

Distribution-specific updates are available from Red Hat, SUSE, and Ubuntu. If immediate patching is not possible, limit local user access to systems using DW DMAMUX hardware and monitor for unusual memory consumption or DMA-related kernel errors (Red Hat CVE, Ubuntu USN-8278-1, Kernel Patches).