# CVE-2026-43344

## Summary

- **CVE ID:** CVE-2026-43344
- **Severity:** MEDIUM
- **CVSS Score:** 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** N/A
- **Published:** May 8, 2026
- **Last Modified:** Sep 14, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:

perf/x86/intel/uncore: Fix die ID init and look up bugs

In snbep_pci2phy_map_init(), in the nr_node_ids > 8 path,
uncore_device_to_die() may return -1 when all CPUs associated
with the UBOX device are offline.

Remove the WARN_ON_ONCE(die_id == -1) check for two reasons:

- The current code breaks out of the loop. This is incorrect because
  pci_get_device() does not guarantee iteration in domain or bus order,
  so additional UBOX devices may be skipped during the scan.

- Returning -EINVAL is incorrect, since marking offline buses with
  die_id == -1 is expected and should not be treated as an error.

Separately, when NUMA is disabled on a NUMA-capable platform,
pcibus_to_node() returns NUMA_NO_NODE, causing uncore_device_to_die()
to return -1 for all PCI devices.  As a result,
spr_update_device_location(), used on Intel SPR and EMR, ignores the
corresponding PMON units and does not add them to the RB tree.

Fix this by using uncore_pcibus_to_dieid(), which retrieves topology
from the UBOX GIDNIDMAP register and works regardless of whether NUMA
is enabled in Linux.  This requires snbep_pci2phy_map_init() to be
added in spr_uncore_pci_init().

Keep uncore_device_to_die() only for the nr_node_ids > 8 case, where
NUMA is expected to be enabled.

## Affected Products

- Linux — Linux (9a7832ce3d920426a36cdd78eda4b3568d4d09e3)
- Linux — Linux (5.12)
- Linux — Linux (0)
- Linux — Linux (6.19.14)
- Linux — Linux (7.0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/6a5dc3ee97581da2907fc7acd62853f07184de67)
- [CNA](https://git.kernel.org/stable/c/a16d1ec4dd0cdcf689f324adde6067083bce9099)
- [CNA](https://git.kernel.org/stable/c/bdb35811ff41a1678620a407056b6372f350028a)
- [CNA](https://git.kernel.org/stable/c/c79ef3342632e71ac8612a2a1cc17ac84dd258b4)
- [CNA](https://git.kernel.org/stable/c/184870af0e73f8ea2577c751fa098681465249f2)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.12%
- **EPSS Percentile:** 1.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._