# CVE-2026-45981: s390/cio: Fix device lifecycle handling in css_alloc_subchannel()

> A use-after-free vulnerability in the Linux kernel s390 channel I/O subsystem allows attackers to potentially execute code or cause a 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:** 27 May 2026
- **Updated:** 1 Jun 2026
- **Also known as:** BELL-CVE-2026-45981, DEBIAN-CVE-2026-45981, GHSA-w3x6-6f6f-54f3, ROOT-OS-DEBIAN-11-CVE-2026-45981, ROOT-OS-UBUNTU-2204-CVE-2026-45981, ROOT-OS-UBUNTU-2404-CVE-2026-45981, UBUNTU-CVE-2026-45981

## What is CVE-2026-45981?

CVE-2026-45981 is a medium-severity use after free vulnerability in Linux kernel, published on 27 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:

s390/cio: Fix device lifecycle handling in css_alloc_subchannel()

`css_alloc_subchannel()` calls `device_initialize()` before setting up
the DMA masks. If `dma_set_coherent_mask()` or `dma_set_mask()` fails,
the error path frees the subchannel structure directly, bypassing
the device model reference counting.

Once `device_initialize()` has been called, the embedded struct device
must be released via `put_device()`, allowing the release callback to
free the container structure.

Fix the error path by dropping the initial device reference with
`put_device()` instead of calling `kfree()` directly.

This ensures correct device lifetime handling and avoids potential
use-after-free or double-free issues.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2026-45981?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-45981?

Apply the vendor's patch.

## Is CVE-2026-45981 being exploited?

There is no known exploitation of CVE-2026-45981 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-2026-45981 and fix it if it is affected.

What it is: CVE-2026-45981 is a medium-severity use after free vulnerability in Linux kernel, published on 27 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-2026-45981 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-2026-45981/ (Markdown: https://insights.sbomify.com/CVE-2026-45981/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45981
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45981
- OSV: https://osv.dev/vulnerability/CVE-2026-45981

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45981/
Summaries are generated and may contain mistakes; the official description above is the record.