In the Linux kernel, the Coresight subsystem failed to preserve system register ETMs and the External Trace Enabler when a CPU powers down. The flaw, documented as “Always save state on power‑down,” caused diagnostic warnings such as “coresight ete0: External agent took claim tag” and led to loss of tracing context. This weakness is rooted in improper initialization and data integrity issues, which are reflected by CWE‑820. The impact is limited to disruption of hardware‑based diagnostics and performance monitoring; it does not appear to grant remote code execution or direct denial of service.

Any Linux kernel release prior to the inclusion of the patch that hard‑codes the sysreg ETM setting is potentially impacted. The kernel CPE indicates that the entire Linux kernel family is affected, but only systems that employ the Coresight hardware tracing subsystem in combination with ACPI‑based CPU power‑down handling are within scope. Administrative or debugging tools that rely on continued tracing state during power cycles would experience interruptions or lost data.

The flaw exists in privileged kernel code and can only be triggered by a CPU power‑down event executed locally. Based on the description, it is inferred that a local attacker with root or equivalent privileges can induce the state loss by orchestrating a power cycle, but there is no evidence that the vulnerability can be exploited remotely or to achieve broader system compromise. The EPSS score is <1 %, and the CVSS v3.1 score is 5.5, which reflects moderate potential impact on availability and diagnostic integrity. The vulnerability is not listed in the CISA KEV catalog.