CVE-2026-80718 mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()
A buffer overflow in the Linux kernel's percpu memory management allows attackers to corrupt memory, potentially leading to system crashes or arbitrary code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80718?
CVE-2026-80718 is a high-severity memory corruption vulnerability in Linux, published on 28 Aug 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:
mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()
In pcpu_create_chunk(), nr_pages is the total contiguous backing allocation, i.e., nr_units * pcpu_unit_pages, but pcpu_chunk_populated() uses it to set chunk->populated, whose size is pcpu_unit_pages, bitmap. Since bit N in chunk->populated means page offset N inside every unit is backed. When nr_units > 1, the function writes beyond chunk->populated. Fix it by using chunk->nr_pages.
It also fixes the global pcpu_nr_empty_pop_pages accounting, since pcpu_balance_free() only iterates up to chunk->nr_pages.
Commit a63d4ac4ab609 ("percpu: make percpu-km set chunk->populated bitmap properly") introduced the bitmap overflow issue. Later, commit b539b87fed37f ("percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated") added pcpu_nr_empty_pop_pages and caused the accounting issue.
Which versions are affected by CVE-2026-80718?
How do I fix CVE-2026-80718?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-80718 being exploited?
There is no known exploitation of CVE-2026-80718 in the wild and no public exploit code.
Sources
Also known as AZL-98138, BELL-CVE-2026-80718, DEBIAN-CVE-2026-80718, GHSA-wv7w-q623-9gwq, UBUNTU-CVE-2026-80718.