The flaw lies in the Linux kernel’s rz_mtu3 module, where repeated writes to the sysfs enable file adjust a runtime power‑management counter without bounds checking. Because the kernel does not validate the current counter state before incrementing or decrementing, repeated writes can cause the counter to under‑flow or over‑increment. The resulting counter mis‑management triggers erroneous hardware register accesses, optionally disabling clocks or prematurely stopping PWM operations. This flaw is a counter manipulation vulnerability (CWE‑911).

The vulnerability affects any Linux kernel that includes the rz_mtu3 driver. No specific kernel version range is listed in the advisory, so all builds that ship the module are potentially affected until the counter logic is fixed.

The vulnerability can only be triggered by a user who can write to the sysfs enable file, which typically requires local privileged or root access. The likely attack vector is a local privileged attacker who performs repeated writes to the enable file—either directly or through a privileged script—to cause the runtime PM counter to mis‑behave. While no EPSS score is available and the flaw is not in the CISA KEV catalog, its absence of counter checks implies a moderate to high likelihood that a locally privileged user could induce a denial of service by disabling hardware functionality or by corrupting the PWM channel. The attack path is straightforward: write the same value to the enable file repeatedly until the counter under‑flows or over‑increments.