CVE-2026-43315 (GCVE-0-2026-43315)
Vulnerability from cvelistv5 – Published: 2026-05-08 13:11 – Updated: 2026-05-08 13:11
VLAI?
Title
KVM: nSVM: Remove a user-triggerable WARN on nested_svm_load_cr3() succeeding
Summary
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.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
b222b0b88162bdef4eceb12a79d5edbbdb23dbfd , < 155ec243ef726f4bc49536fa0bfb565dc011ab17
(git)
Affected: b222b0b88162bdef4eceb12a79d5edbbdb23dbfd , < 580ea57840864d40e019bc13fd26afdc8d510a2f (git) Affected: b222b0b88162bdef4eceb12a79d5edbbdb23dbfd , < deb8f6dfd31d94b18dbeeaa8c01fbec5fc70fd2b (git) Affected: b222b0b88162bdef4eceb12a79d5edbbdb23dbfd , < ce904c8a5bbe697eae0f7e34b07095bd7a6dee19 (git) Affected: b222b0b88162bdef4eceb12a79d5edbbdb23dbfd , < 969e5e13ff5c18603f21d1f9f64ec9194e141ac0 (git) Affected: b222b0b88162bdef4eceb12a79d5edbbdb23dbfd , < ebb2ab4f1c87d6b52776292cf7dc16aea48e95f8 (git) Affected: b222b0b88162bdef4eceb12a79d5edbbdb23dbfd , < fc3ba56385d03501eb582e4b86691ba378e556f9 (git) |
|||||||
|
|||||||||
{
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"status": "unaffected",
"version": "5.15.202",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.1.165",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.128",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.75",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.18.16",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.19.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
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"nodes": [
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"vulnerable": true
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: nSVM: Remove a user-triggerable WARN on nested_svm_load_cr3() succeeding\n\nDrop the WARN in svm_set_nested_state() on nested_svm_load_cr3() failing\nas it is trivially easy to trigger from userspace by modifying CPUID after\nloading CR3. E.g. modifying the state restoration selftest like so:\n\n --- tools/testing/selftests/kvm/x86/state_test.c\n +++ tools/testing/selftests/kvm/x86/state_test.c\n @@ -280,7 +280,16 @@ int main(int argc, char *argv[])\n\n /* Restore state in a new VM. */\n vcpu = vm_recreate_with_one_vcpu(vm);\n - vcpu_load_state(vcpu, state);\n +\n + if (stage == 4) {\n + state-\u003esregs.cr3 = BIT(44);\n + vcpu_load_state(vcpu, state);\n +\n + vcpu_set_cpuid_property(vcpu, X86_PROPERTY_MAX_PHY_ADDR, 36);\n + __vcpu_nested_state_set(vcpu, \u0026state-\u003enested);\n + } else {\n + vcpu_load_state(vcpu, state);\n + }\n\n /*\n * Restore XSAVE state in a dummy vCPU, first without doing\n\ngenerates:\n\n WARNING: CPU: 30 PID: 938 at arch/x86/kvm/svm/nested.c:1877 svm_set_nested_state+0x34a/0x360 [kvm_amd]\n Modules linked in: kvm_amd kvm irqbypass [last unloaded: kvm]\n CPU: 30 UID: 1000 PID: 938 Comm: state_test Tainted: G W 6.18.0-rc7-58e10b63777d-next-vm\n Tainted: [W]=WARN\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n RIP: 0010:svm_set_nested_state+0x34a/0x360 [kvm_amd]\n Call Trace:\n \u003cTASK\u003e\n kvm_arch_vcpu_ioctl+0xf33/0x1700 [kvm]\n kvm_vcpu_ioctl+0x4e6/0x8f0 [kvm]\n __x64_sys_ioctl+0x8f/0xd0\n do_syscall_64+0x61/0xad0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\nSimply delete the WARN instead of trying to prevent userspace from shoving\n\"illegal\" state into CR3. For better or worse, KVM\u0027s ABI allows userspace\nto set CPUID after SREGS, and vice versa, and KVM is very permissive when\nit comes to guest CPUID. I.e. attempting to enforce the virtual CPU model\nwhen setting CPUID could break userspace. Given that the WARN doesn\u0027t\nprovide any meaningful protection for KVM or benefit for userspace, simply\ndrop it even though the odds of breaking userspace are minuscule.\n\nOpportunistically delete a spurious newline."
}
],
"providerMetadata": {
"dateUpdated": "2026-05-08T13:11:31.784Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/155ec243ef726f4bc49536fa0bfb565dc011ab17"
},
{
"url": "https://git.kernel.org/stable/c/580ea57840864d40e019bc13fd26afdc8d510a2f"
},
{
"url": "https://git.kernel.org/stable/c/deb8f6dfd31d94b18dbeeaa8c01fbec5fc70fd2b"
},
{
"url": "https://git.kernel.org/stable/c/ce904c8a5bbe697eae0f7e34b07095bd7a6dee19"
},
{
"url": "https://git.kernel.org/stable/c/969e5e13ff5c18603f21d1f9f64ec9194e141ac0"
},
{
"url": "https://git.kernel.org/stable/c/ebb2ab4f1c87d6b52776292cf7dc16aea48e95f8"
},
{
"url": "https://git.kernel.org/stable/c/fc3ba56385d03501eb582e4b86691ba378e556f9"
}
],
"title": "KVM: nSVM: Remove a user-triggerable WARN on nested_svm_load_cr3() succeeding",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-43315",
"datePublished": "2026-05-08T13:11:31.784Z",
"dateReserved": "2026-05-01T14:12:56.001Z",
"dateUpdated": "2026-05-08T13:11:31.784Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-43315\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-08T14:16:39.977\",\"lastModified\":\"2026-05-08T14:16:39.977\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nKVM: nSVM: Remove a user-triggerable WARN on nested_svm_load_cr3() succeeding\\n\\nDrop the WARN in svm_set_nested_state() on nested_svm_load_cr3() failing\\nas it is trivially easy to trigger from userspace by modifying CPUID after\\nloading CR3. E.g. modifying the state restoration selftest like so:\\n\\n --- tools/testing/selftests/kvm/x86/state_test.c\\n +++ tools/testing/selftests/kvm/x86/state_test.c\\n @@ -280,7 +280,16 @@ int main(int argc, char *argv[])\\n\\n /* Restore state in a new VM. */\\n vcpu = vm_recreate_with_one_vcpu(vm);\\n - vcpu_load_state(vcpu, state);\\n +\\n + if (stage == 4) {\\n + state-\u003esregs.cr3 = BIT(44);\\n + vcpu_load_state(vcpu, state);\\n +\\n + vcpu_set_cpuid_property(vcpu, X86_PROPERTY_MAX_PHY_ADDR, 36);\\n + __vcpu_nested_state_set(vcpu, \u0026state-\u003enested);\\n + } else {\\n + vcpu_load_state(vcpu, state);\\n + }\\n\\n /*\\n * Restore XSAVE state in a dummy vCPU, first without doing\\n\\ngenerates:\\n\\n WARNING: CPU: 30 PID: 938 at arch/x86/kvm/svm/nested.c:1877 svm_set_nested_state+0x34a/0x360 [kvm_amd]\\n Modules linked in: kvm_amd kvm irqbypass [last unloaded: kvm]\\n CPU: 30 UID: 1000 PID: 938 Comm: state_test Tainted: G W 6.18.0-rc7-58e10b63777d-next-vm\\n Tainted: [W]=WARN\\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\\n RIP: 0010:svm_set_nested_state+0x34a/0x360 [kvm_amd]\\n Call Trace:\\n \u003cTASK\u003e\\n kvm_arch_vcpu_ioctl+0xf33/0x1700 [kvm]\\n kvm_vcpu_ioctl+0x4e6/0x8f0 [kvm]\\n __x64_sys_ioctl+0x8f/0xd0\\n do_syscall_64+0x61/0xad0\\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\\n\\nSimply delete the WARN instead of trying to prevent userspace from shoving\\n\\\"illegal\\\" state into CR3. For better or worse, KVM\u0027s ABI allows userspace\\nto set CPUID after SREGS, and vice versa, and KVM is very permissive when\\nit comes to guest CPUID. I.e. attempting to enforce the virtual CPU model\\nwhen setting CPUID could break userspace. Given that the WARN doesn\u0027t\\nprovide any meaningful protection for KVM or benefit for userspace, simply\\ndrop it even though the odds of breaking userspace are minuscule.\\n\\nOpportunistically delete a spurious newline.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/155ec243ef726f4bc49536fa0bfb565dc011ab17\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/580ea57840864d40e019bc13fd26afdc8d510a2f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/969e5e13ff5c18603f21d1f9f64ec9194e141ac0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ce904c8a5bbe697eae0f7e34b07095bd7a6dee19\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/deb8f6dfd31d94b18dbeeaa8c01fbec5fc70fd2b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ebb2ab4f1c87d6b52776292cf7dc16aea48e95f8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/fc3ba56385d03501eb582e4b86691ba378e556f9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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