Bug 2554944 (CVE-2026-98637)

Summary: CVE-2026-98637 kernel: KVM: arm64: Do not clear VM-wide SVE feature on vCPU init failure
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's KVM (Kernel-based Virtual Machine) subsystem for ARM64. When a virtual CPU (vCPU) fails to initialize Scalable Vector Extension (SVE) support, feature flags are improperly handled, leaving subsequent vCPUs in an inconsistent state without allocated memory. A guest virtual machine can trigger this issue during floating-point operations to cause a null pointer dereference in the hypervisor, resulting in a Denial of Service (DoS) via a system crash.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-10-18 15:34:24 UTC 
In the Linux kernel, the following vulnerability has been resolved:

KVM: arm64: Do not clear VM-wide SVE feature on vCPU init failure

pkvm_vcpu_init_sve() clears KVM_ARM_VCPU_SVE in kvm->arch.vcpu_features
when it fails, but vcpu_has_sve() tests KVM_ARCH_FLAG_GUEST_HAS_SVE,
which is left set. Later vCPUs on that VM then skip the SVE setup and
register with a NULL sve_state, which the guest's first FP access hands
to sve_load_state().

Return the error without touching vcpu_features.