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

Status: published. Published: 2026-04-24. Updated: 2026-11-05.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 084ea4d611a3d00ee3930400b262240e10895900; < 48eda93e50f8361dee8e261fe55d0b31714e1e56 (affected, git); ≥ 084ea4d611a3d00ee3930400b262240e10895900; < 1eb35c54cd81cf874ce7d69e3dbfb162f211b8bd (affected, git); ≥ 084ea4d611a3d00ee3930400b262240e10895900; < b36b0e804aee5f20c6798dbeaeaa7cfdb7c6cf88 (affected, git); ≥ 084ea4d611a3d00ee3930400b262240e10895900; < 43ac2d18db1131df0a89993f709131ebfc29f3bd (affected, git); ≥ 084ea4d611a3d00ee3930400b262240e10895900; < b00be77302d7ec4ad0367bb236494fce7172b730 (affected, git). Source: CNA: Linux
- Linux / Linux: 5.7 (affected); ≥ 0; < 5.7 (unaffected, semver); ≥ 6.1.191; ≤ 6.1.* (unaffected, semver); ≥ 6.6.160; ≤ 6.6.* (unaffected, semver); ≥ 6.18.21; ≤ 6.18.* (unaffected, semver); ≥ 6.19.11; ≤ 6.19.* (unaffected, semver); ≥ 7.0; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.16% as of 2026-11-05; percentile 5.06%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/48eda93e50f8361dee8e261fe55d0b31714e1e56 (CNA: Linux)

- https://git.kernel.org/stable/c/1eb35c54cd81cf874ce7d69e3dbfb162f211b8bd (CNA: Linux)

- https://git.kernel.org/stable/c/b36b0e804aee5f20c6798dbeaeaa7cfdb7c6cf88 (CNA: Linux)

- https://git.kernel.org/stable/c/43ac2d18db1131df0a89993f709131ebfc29f3bd (CNA: Linux)

- https://git.kernel.org/stable/c/b00be77302d7ec4ad0367bb236494fce7172b730 (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-31568; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-31568; retrieved 2026-11-05; source updated Not reported

Revision: 871d060caf0350b63aae39a7b45eebb01ad6c32304da00b2025da022cad4ef3f

Canonical: https://y2.dev/cve/CVE-2026-31568

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.