A defect in the Linux kernel’s uncore device initialization caused the die identifier to be incorrectly reported as –1 when all CPUs linked to a UBOX device were offline, or when NUMA was disabled. This bad value broke device‑scanning loops and caused performance monitoring (PMON) units on Intel SPR and EMR platforms to be omitted from the system’s runtime data structures, resulting in incomplete hardware topology and loss of accurate performance data rather than a direct security breach.

All Linux kernel installations that incorporated the snbep_pci2phy_map_init path prior to the fix are affected. The bug spans all kernel versions hosted under the Linux:Linux CNA that contain the uninitialized die ID logic within the perf/x86/intel/uncore subsystem. Updated kernels that include the referenced commits correct the logic and are not vulnerable.

The CVSS score of 5.5 indicates moderate severity, and no EPSS probability is available; the vulnerability is not listed in the CISA KEV catalog. Based on the description, the attack vector is most likely local during system boot or when an administrator or privileged process triggers a reseed of the UBOX topology. While it does not provide direct code execution or data exfiltration, the flaw can be exploited to foil performance monitoring and potentially hide hardware issues from system administrators, so the severity is moderate at most, with exploitable conditions limited to environments that rely on full PMON coverage for monitoring or debugging.