SB20261022240 - Improper handling of exceptional conditions in Linux kernel kvm s390

Description

This security bulletin contains information about 1 vulnerability.

1) Improper handling of exceptional conditions (CVE-ID: CVE-2026-98653)

CWE-ID: CWE-755 - Improper Handling of Exceptional Conditions

CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

The vulnerability allows a local user to potentially cause a denial of service affecting nested guest execution.

The vulnerability exists due to improper handling of missing memory mappings in the Linux kernel's s390 KVM shadow fault handling when shadowing nested guest memory that is not present in the parent guest gmap. A local user can trigger this condition through nested guest memory accesses to cause an unexpected -ENOENT error to propagate to userspace, potentially disrupting nested guest execution.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/94c43c7df46433ed4d1e18f13770b019ba977bd8
• https://git.kernel.org/stable/c/faff4c8ff3dbec6d71b89dd281a0d17c4478fa44