CVE-2026-43344 perf/x86/intel/uncore: Fix die ID init and look up bugs

What is CVE-2026-43344?

CVE-2026-43344 is a medium-severity denial of service vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Weakness: CWE-617

Which versions are affected by CVE-2026-43344?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-43344?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-43344 being exploited?

There is no known exploitation of CVE-2026-43344 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-86163, BELL-CVE-2026-43344, DEBIAN-CVE-2026-43344, GHSA-m424-x6wr-wwgw, ROOT-OS-DEBIAN-12-CVE-2026-43344, ROOT-OS-DEBIAN-13-CVE-2026-43344 and 3 more.