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CVE-2026-43315 Affecting kernel-rt-64k-debug-devel-matched package, versions *

Severity

 Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.02% (8th percentile)

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  • Snyk IDSNYK-RHEL9-KERNELRT64KDEBUGDEVELMATCHED-16582409
  • published9 May 2026
  • disclosed8 May 2026
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Introduced: 8 May 2026

NewCVE-2026-43315  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-rt-64k-debug-devel-matched.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-debug-devel-matched package and not the kernel-rt-64k-debug-devel-matched package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

KVM: nSVM: Remove a user-triggerable WARN on nested_svm_load_cr3() succeeding

Drop the WARN in svm_set_nested_state() on nested_svm_load_cr3() failing as it is trivially easy to trigger from userspace by modifying CPUID after loading CR3. E.g. modifying the state restoration selftest like so:

--- tools/testing/selftests/kvm/x86/state_test.c +++ tools/testing/selftests/kvm/x86/state_test.c @@ -280,7 +280,16 @@ int main(int argc, char *argv[])

             /* Restore state in a new VM.  */
              vcpu = vm_recreate_with_one_vcpu(vm);

  •           vcpu_load_state(vcpu, state);

  •           if (stage == 4) {

  •                   state->sregs.cr3 = BIT(44);

  •                   vcpu_load_state(vcpu, state);

  •                   vcpu_set_cpuid_property(vcpu, X86_PROPERTY_MAX_PHY_ADDR, 36);

  •                   __vcpu_nested_state_set(vcpu, &state->nested);

  •           } else {

  •                   vcpu_load_state(vcpu, state);

  •           }


          /*
       * Restore XSAVE state in a dummy vCPU, first without doing

generates:

WARNING: CPU: 30 PID: 938 at arch/x86/kvm/svm/nested.c:1877 svm_set_nested_state+0x34a/0x360 [kvm_amd] Modules linked in: kvm_amd kvm irqbypass [last unloaded: kvm] CPU: 30 UID: 1000 PID: 938 Comm: state_test Tainted: G W 6.18.0-rc7-58e10b63777d-next-vm Tainted: [W]=WARN Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:svm_set_nested_state+0x34a/0x360 [kvm_amd] Call Trace: <TASK> kvm_arch_vcpu_ioctl+0xf33/0x1700 [kvm] kvm_vcpu_ioctl+0x4e6/0x8f0 [kvm] __x64_sys_ioctl+0x8f/0xd0 do_syscall_64+0x61/0xad0 entry_SYSCALL_64_after_hwframe+0x4b/0x53

Simply delete the WARN instead of trying to prevent userspace from shoving "illegal" state into CR3. For better or worse, KVM's ABI allows userspace to set CPUID after SREGS, and vice versa, and KVM is very permissive when it comes to guest CPUID. I.e. attempting to enforce the virtual CPU model when setting CPUID could break userspace. Given that the WARN doesn't provide any meaningful protection for KVM or benefit for userspace, simply drop it even though the odds of breaking userspace are minuscule.

Opportunistically delete a spurious newline.

CVSS Base Scores

version 3.1