# CVE-2026-31749: comedi: ni_atmio16d: Fix invalid clean-up after failed attach

> A null pointer dereference in the ni_atmio16d driver cleanup path can cause a kernel crash if attach fails, leading to denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **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:** Yes
- **Published:** 1 May 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-31749, DEBIAN-CVE-2026-31749, GHSA-jgc9-fr2g-9r52, ROOT-OS-DEBIAN-11-CVE-2026-31749, ROOT-OS-UBUNTU-2204-CVE-2026-31749, ROOT-OS-UBUNTU-2404-CVE-2026-31749, UBUNTU-CVE-2026-31749

## What is CVE-2026-31749?

CVE-2026-31749 is a medium-severity vulnerability in Linux kernel, published on 1 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:

comedi: ni_atmio16d: Fix invalid clean-up after failed attach

If the driver's COMEDI "attach" handler function (`atmio16d_attach()`)
returns an error, the COMEDI core will call the driver's "detach"
handler function (`atmio16d_detach()`) to clean up.  This calls
`reset_atmio16d()` unconditionally, but depending on where the error
occurred in the attach handler, the device may not have been
sufficiently initialized to call `reset_atmio16d()`.  It uses
`dev->iobase` as the I/O port base address and `dev->private` as the
pointer to the COMEDI device's private data structure.  `dev->iobase`
may still be set to its initial value of 0, which would result in
undesired writes to low I/O port addresses.  `dev->private` may still be
`NULL`, which would result in null pointer dereferences.

Fix `atmio16d_detach()` by checking that `dev->private` is valid
(non-null) before calling `reset_atmio16d()`.  This implies that
`dev->iobase` was set correctly since that is set up before
`dev->private`.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-31749?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31749?

Apply the vendor's patch.

## Is CVE-2026-31749 being exploited?

There is no known exploitation of CVE-2026-31749 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31749 and fix it if it is affected.

What it is: CVE-2026-31749 is a medium-severity vulnerability in Linux kernel, published on 1 May 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-2026-31749 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-31749/ (Markdown: https://insights.sbomify.com/CVE-2026-31749/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31749
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31749
- OSV: https://osv.dev/vulnerability/CVE-2026-31749

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31749/
Summaries are generated and may contain mistakes; the official description above is the record.