# CVE-2026-31568: s390/mm: Add missing secure storage access fixups for donated memory

> A flaw in the Linux kernel s390 memory management causes infinite exception loops for donated secure storage, leading to system denial of service.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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:** 24 Apr 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-83786, BELL-CVE-2026-31568, DEBIAN-CVE-2026-31568, GHSA-g33j-4pfw-cr34, ROOT-OS-DEBIAN-11-CVE-2026-31568, ROOT-OS-DEBIAN-12-CVE-2026-31568, ROOT-OS-DEBIAN-13-CVE-2026-31568, ROOT-OS-UBUNTU-2204-CVE-2026-31568, ROOT-OS-UBUNTU-2404-CVE-2026-31568, UBUNTU-CVE-2026-31568

## What is CVE-2026-31568?

CVE-2026-31568 is a high-severity denial of service vulnerability in Linux kernel, published on 24 Apr 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/mm: Add missing secure storage access fixups for donated memory

There are special cases where secure storage access exceptions happen
in a kernel context for pages that don't have the PG_arch_1 bit
set. That bit is set for non-exported guest secure storage (memory)
but is absent on storage donated to the Ultravisor since the kernel
isn't allowed to export donated pages.

Prior to this patch we would try to export the page by calling
arch_make_folio_accessible() which would instantly return since the
arch bit is absent signifying that the page was already exported and
no further action is necessary. This leads to secure storage access
exception loops which can never be resolved.

With this patch we unconditionally try to export and if that fails we
fixup.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-31568?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31568?

Apply the vendor's patch.

## Is CVE-2026-31568 being exploited?

There is no known exploitation of CVE-2026-31568 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-2026-31568 and fix it if it is affected.

What it is: CVE-2026-31568 is a high-severity denial of service vulnerability in Linux kernel, published on 24 Apr 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-2026-31568 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-2026-31568/ (Markdown: https://insights.sbomify.com/CVE-2026-31568/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31568
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31568
- OSV: https://osv.dev/vulnerability/CVE-2026-31568

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31568/
Summaries are generated and may contain mistakes; the official description above is the record.