CVE-2026-80718

Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source

AV:LAttack vector, local

pcpu_create_chunk() is reached only when the kernel dynamic percpu allocator creates a new chunk via pcpu_alloc_noprof() or pcpu_balance_populated(); both require local syscalls driving __alloc_percpu() exhaustion, and percpu-km applies only on NOMMU/UP kernels with no remote packet path into this code.

AC:LAttack complexity, low

On affected SMP NOMMU builds where nr_units>1, an attacker can deterministically force pcpu_create_chunk() by spraying percpu-consuming allocations (e.g., repeated socket() or BPF percpu map creation) until existing chunks are full; no race or victim state outside attacker control is needed.

PR:LPrivileges required, low

Dynamic percpu allocation is reachable with basic local user access; unprivileged attackers can obtain effective capability via user namespaces (unshare -Urn) plus CAP_NET_RAW-class socket paths or CAP_BPF where enabled, matching percpu-spray patterns in similar allocator CVEs.

UI:NUser interaction, none

The attacker drives percpu exhaustion and new-chunk creation entirely from its own processes via repeated local syscalls; no victim mount, file open, or administrator interaction is required.

S:UScope, unchanged

The bitmap overflow corrupts kernel kmalloc slab objects and percpu bookkeeping within the same kernel security domain; this is standard kernel heap corruption, not a VM, IOMMU, or sandbox boundary escape.

C:HConfidentiality impact, high

bitmap_set() writes up to (nr_units*pcpu_unit_pages) bits into chunk->populated[] sized for only pcpu_unit_pages, overflowing the kzalloc allocation in pcpu_alloc_chunk() and exposing or corrupting adjacent kernel heap memory.

I:HIntegrity impact, high

The same out-of-bounds write corrupts neighboring slab objects and inflates nr_populated/nr_empty_pop_pages accounting, providing attacker-influenced heap metadata corruption exploitable for arbitrary kernel writes and privilege escalation.

A:HAvailability impact, high

Slab overflow during chunk initialization can immediately oops or panic the kernel and leaves corrupted allocator state that causes subsequent percpu operations to fault, consistent with rubric guidance for heap corruption bugs.