CVE-2026-43315KVM: nSVM: Remove a user-triggerable WARN on nested_svm_load_cr3() succeeding

Description

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.

Timeline

Scores

EPSS (exploitation in 30 days)

0.13% · top 97% of all CVEs (14 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.

Affected products

• Linux · Linux

  • affected b222b0b88162bdef4eceb12a79d5edbbdb23dbfd – < 155ec243ef726f4bc49536fa0bfb565dc011ab17
  • affected b222b0b88162bdef4eceb12a79d5edbbdb23dbfd – < 580ea57840864d40e019bc13fd26afdc8d510a2f
  • affected b222b0b88162bdef4eceb12a79d5edbbdb23dbfd – < deb8f6dfd31d94b18dbeeaa8c01fbec5fc70fd2b
  • affected b222b0b88162bdef4eceb12a79d5edbbdb23dbfd – < ce904c8a5bbe697eae0f7e34b07095bd7a6dee19
  • affected b222b0b88162bdef4eceb12a79d5edbbdb23dbfd – < 969e5e13ff5c18603f21d1f9f64ec9194e141ac0
  • affected b222b0b88162bdef4eceb12a79d5edbbdb23dbfd – < ebb2ab4f1c87d6b52776292cf7dc16aea48e95f8
  • affected b222b0b88162bdef4eceb12a79d5edbbdb23dbfd – < fc3ba56385d03501eb582e4b86691ba378e556f9

• Linux · Linux

  • affected 5.14
  • unaffected < 5.14
  • unaffected 5.15.202 – ≤ 5.15.*
  • unaffected 6.1.165 – ≤ 6.1.*
  • unaffected 6.6.128 – ≤ 6.6.*
  • unaffected 6.12.75 – ≤ 6.12.*
  • unaffected 6.18.16 – ≤ 6.18.*
  • unaffected 6.19.6 – ≤ 6.19.*
  • unaffected 7.0 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-28585 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-43315](https://cveledger.app/badge/CVE-2026-43315.svg)](https://cveledger.app/cve/CVE-2026-43315)

Record last updated 6 Nov 2026, 15:42 UTC.