Impact
The bug occurs in the Linux kernel’s cpuidle subsystem when only one idle state is registered, typically the polling state (state 0). The ladder governor mistakenly treats a nonexistent state 1 as the first usable state, causing an out‑of‑bounds index and a NULL enter callback. This results in a kernel panic, a classic denial‑of‑service scenario. The flaw manifests as a null pointer dereference (CWE‑476) and an out‑of‑bounds index (CWE‑788).
Affected Systems
All Linux kernel builds running on platforms that expose just a single idle state, such as PowerNV systems without a power‑management device tree node, are affected. The vulnerability exists in any kernel that has not incorporated the recent bail‑out in cpuidle_select for state_count <= 1.
Risk and Exploitability
The CVSS score is 5.5, the EPSS score is < 1%, and the vulnerability is not listed in the CISA KEV catalog. Because the flaw is triggered by firmware or boot‑time configuration rather than a remote interface, the attack vector is local; an attacker with physical or local access who can force a one‑state configuration or boot the affected hardware will cause an immediate system crash. No public exploits have been reported.
OpenCVE Enrichment
Debian DLA