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.
- 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
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
Which versions are affected by CVE-2026-31568?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31568?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
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
Sources
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 and 4 more.