CVE-2026-31568: linux Out-of-bounds Read

Vulnerability summary

CVE-2026-31568 is a high (CVSS 7.1) Out-of-bounds Read vulnerability in linux. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 5.3% of scored vulnerabilities.

Timeline

1. 24-04-2026
   PublishedVulnerability first disclosed.
2. 21-10-2026
   Last modifiedVulnerability information updated.

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.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.