CVE-2026-72212 mm/memory_hotplug: fix incorrect altmap passing in error path
A bug in the Linux kernel memory hotplug error path causes memory corruption and potential code execution when memmap_on_memory is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72212?
CVE-2026-72212 is a memory corruption vulnerability in Linux, published on 15 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/memory_hotplug: fix incorrect altmap passing in error path
In create_altmaps_and_memory_blocks(), when arch_add_memory() succeeds with memmap_on_memory enabled, the vmemmap pages are allocated from params.altmap. If create_memory_block_devices() subsequently fails, the error path calls arch_remove_memory() with a NULL altmap instead of params.altmap.
This is a bug that could lead to memory corruption. Since altmap is NULL, vmemmap_free() falls back to freeing the vmemmap pages into the system buddy allocator via free_pages() instead of the altmap. arch_remove_memory() then immediately destroys the physical linear mapping for this memory. This injects unowned pages into the buddy allocator, causing machine checks or memory corruption if the system later attempts to allocate and use those freed pages.
Fix this by passing params.altmap to arch_remove_memory() in the error path.
Which versions are affected by CVE-2026-72212?
How do I fix CVE-2026-72212?
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-2026-72212 being exploited?
There is no known exploitation of CVE-2026-72212 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72212, DEBIAN-CVE-2026-72212, GHSA-w9xv-r954-cxrq, UBUNTU-CVE-2026-72212.