Out-of-bounds Read in Linux

CVE-2026-31568

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.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (5.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 5.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-31568: held from 0.001 to 0.002.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.000

Affected products

  • Linux — versions 084ea4d611a3d00ee3930400b262240e10895900, 5.7, 0
  • Linux Kernel — versions 5.7, 7.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-31568?
CVE-2026-31568 is a high-severity vulnerability in Linux, classified under Out-of-bounds Read. CVSS score: 7.1/10. Published 2026-04-24.
How severe is CVE-2026-31568?
High severity. CVSS v3 base score is 7.1 out of 10.