# CVE-2026-93172: mm/mm_init: handle alloc_percpu failure in free_area_init_core_hotplug

> A missing allocation check in the Linux kernel memory management subsystem causes a NULL pointer dereference during node hotplug, leading to a system crash.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-102893, BELL-CVE-2026-93172, DEBIAN-CVE-2026-93172, GHSA-3775-xr2m-86hx, UBUNTU-CVE-2026-93172

## What is CVE-2026-93172?

CVE-2026-93172 is a vulnerability in Linux, published on 17 Sep 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/mm_init: handle alloc_percpu failure in free_area_init_core_hotplug

We miss a failed allocation check for pgdat->per_cpu_nodestats, which
results in a NULL deref when we offset into the per-cpu area.

Propagate -ENOMEM up the stack and leave per_cpu_nodestats pointing
at boot_nodestats so a later online can retry the allocation.

hotadd_init_pgdat() returns NULL on failure, which __try_online_node()
already maps to -ENOMEM.

On failure nothing needs to be unwound:
  - the node is never marked online
  - per_cpu_nodestats is left pointing at boot_nodestats
  - __add_memory_resource() cleans up pending memblock resources
  - later online attempts retry the per_cpu_nodestats allocation

## Which versions are affected by CVE-2026-93172?


## How do I fix CVE-2026-93172?

Apply the vendor's patch.

## Is CVE-2026-93172 being exploited?

There is no known exploitation of CVE-2026-93172 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93172 and fix it if it is affected.

What it is: CVE-2026-93172 is a vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-93172 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-93172/ (Markdown: https://insights.sbomify.com/CVE-2026-93172/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93172
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93172
- OSV: https://osv.dev/vulnerability/CVE-2026-93172

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93172/
Summaries are generated and may contain mistakes; the official description above is the record.