CVE-2026-43079

Vulnerability: The Intel uncore performance monitoring driver (perf/x86/intel/uncore) in the Linux kernel fails to skip the PCI discovery table for dies that have all their CPUs offline. When NUMA is disabled and the system boots with fewer CPUs than the number of CPUs in die 0, the driver continues to parse the discovery table for offline dies. This leads to an array overflow at pmu->boxes[die] = box in uncore_pci_pmu_register(), triggering a warning or other undefined behavior [1] [2] [3] [4].

Exploitation

Exploitation: The vulnerability is triggered during system boot when the uncore driver initializes. No special privileges or network access are required; it occurs automatically in a specific hardware configuration (NUMA disabled, fewer CPUs online than die 0 contains). The attack surface is limited to systems with Intel processors that use the uncore PMU and have the described topology. An attacker cannot directly trigger this condition to cause a denial of service by crashing the system or corrupting memory [1] [2] [3] [4].

## t: The primary impact is a kernel warning or memory corruption due to the array overflow, which can cause a system crash or crash. This could lead to a denial of service (system instability or panic). In some cases, the overflow might be exploitable for privilege escalation, but the description and references do not confirm only the warning and potential for other issues [1] [2] [3] [4].

##

Mitigation: The fix is to skip the discovery table for offline dies, preventing the overflow. The patch has been applied to the Linux kernel stable branches. Users should update to a kernel version containing the commit (e.g., f34feda8e0c9f71, cfab2c817d2e, 7a2cb02437d9, or 6cfc187d85f1) [1] [2] [3] [4]. No workaround is available other than upgrading.