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CVE-2026-31568
s390/mm: Add missing secure storage access fixups for donated memory
Published 2026-04-24 (6 months ago) by the Linux kernel CNA. Subsystem arch/s390. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-31568 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 6.19.11-1 | Update the kernel and reboot. Fixed in 6.19.11-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.19.11-1 | Update the kernel and reboot. Fixed in 6.19.11-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
arch/s390/mm/fault.c
- What this is
- S390 MMMAINTAINERS section matched on arch/s390/mm · linux-s390@vger.kernel.org · Supported
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS Debian linux-config packages
Signals
- Published
- 2026-04-24 (6 months ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.16%, higher than 5.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- arch/s390
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.7 | 6.18.21 | b36b0e804aee |
| 5.7 | 6.19.11 | 43ac2d18db11 |
| 5.7 | 7.0 | b00be77302d7 |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-31568, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.