KVM s390 shadow fault handling wrongly returns errors in Linux kernel
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Fixed
No CVSS vector from any source. Fix status from CNA.
Summary
The KVM s390 code in the Linux kernel, from version 7.0, mishandles nested guest memory that is being shadowed but is not present in the parent guest mapping. In _gaccess_shadow_fault(), the lookup returns -ENOENT, and that error reaches userspace instead of the missing page being linked.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Fix _gaccess_shadow_fault() In some circumstances, it is possible that the page of nested guest memory that is being shadowed is not present at all in the parent guest gmap. dat_entry_walk() will not find any leaf entry and return with -ENOENT, which will erroneously be propagated all the way to userspace. Fix by manually calling gmap_link() on the memory of the nested guest that is being shadowed if the mapping was not already present.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
The fixed versions for Linux kernel are 7.2.9 and 7.3.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 7.2.9, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 7 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98653
- 2026-10-18 Alias added: GHSA-v97x-654r-4f82
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-22 Affected versions changed · Red Hat
- 2026-10-22 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
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Sources
- CVE-2026-98653 · CVE Program
- CVE-2026-98653 · NVD
- FIRST EPSS
- GHSA-v97x-654r-4f82 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98653 · Red Hat security data · CC BY 4.0
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