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

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于svm_set_nested_state函数中nested_svm_load_cr3失败时触发WARN，用户可通过修改CPUID轻易触发。

AI Predicted 5.5 Difficulty: Trivial EPSS 0.17% · P6

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux b222b0b88162bdef4eceb12a79d5edbbdb23dbfd< 155ec243ef726f4bc49536fa0bfb565dc011ab17 affected
b222b0b88162bdef4eceb12a79d5edbbdb23dbfd< 580ea57840864d40e019bc13fd26afdc8d510a2f affected
b222b0b88162bdef4eceb12a79d5edbbdb23dbfd< deb8f6dfd31d94b18dbeeaa8c01fbec5fc70fd2b affected
b222b0b88162bdef4eceb12a79d5edbbdb23dbfd< ce904c8a5bbe697eae0f7e34b07095bd7a6dee19 affected
b222b0b88162bdef4eceb12a79d5edbbdb23dbfd< 969e5e13ff5c18603f21d1f9f64ec9194e141ac0 affected
b222b0b88162bdef4eceb12a79d5edbbdb23dbfd< ebb2ab4f1c87d6b52776292cf7dc16aea48e95f8 affected
b222b0b88162bdef4eceb12a79d5edbbdb23dbfd< fc3ba56385d03501eb582e4b86691ba378e556f9 affected
5.14 affected
… +8 more rows
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I. Basic Information for CVE-2026-43315

Vulnerability Information
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Vulnerability Title
KVM: nSVM: Remove a user-triggerable WARN on nested_svm_load_cr3() succeeding
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于svm_set_nested_state函数中nested_svm_load_cr3失败时触发WARN，用户可通过修改CPUID轻易触发。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux b222b0b88162bdef4eceb12a79d5edbbdb23dbfd ~ 155ec243ef726f4bc49536fa0bfb565dc011ab17 -
Linux Linux 5.14 -

II. Public POCs for CVE-2026-43315

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III. Intelligence Information for CVE-2026-43315

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Patches & Fixes for CVE-2026-43315 (7)

Same Patch Batch · Linux · 2026-05-08 · 197 CVEs total

CVE-2026-43341 9.8 CRITICAL net/ipv6: ioam6: prevent schema length wraparound in trace fill
CVE-2026-43402 9.8 CRITICAL kthread: consolidate kthread exit paths to prevent use-after-free
CVE-2026-43414 9.8 CRITICAL scsi: qla2xxx: Completely fix fcport double free
CVE-2026-43384 9.8 CRITICAL net/tcp-ao: Fix MAC comparison to be constant-time
CVE-2026-43304 9.8 CRITICAL libceph: define and enforce CEPH_MAX_KEY_LEN
CVE-2026-43379 9.8 CRITICAL ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close()
CVE-2026-43376 9.8 CRITICAL ksmbd: fix use-after-free by using call_rcu() for oplock_info
CVE-2026-43465 9.8 CRITICAL net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ
CVE-2026-43378 9.8 CRITICAL smb: server: fix use-after-free in smb2_open()
CVE-2026-43383 9.4 CRITICAL net/tcp-md5: Fix MAC comparison to be constant-time
CVE-2026-43406 9.1 CRITICAL libceph: prevent potential out-of-bounds reads in process_message_header()
CVE-2026-43407 9.1 CRITICAL libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply()
CVE-2026-43284 8.8 HIGH xfrm: esp: avoid in-place decrypt on shared skb frags
CVE-2026-43334 8.8 HIGH Bluetooth: SMP: force responder MITM requirements before building the pairing response
CVE-2026-43322 8.8 HIGH Bluetooth: hci_sync: Fix UAF in le_read_features_complete
CVE-2026-43403 8.8 HIGH nsfs: tighten permission checks for ns iteration ioctls
CVE-2026-43391 8.8 HIGH nsfs: tighten permission checks for handle opening
CVE-2026-43291 8.3 HIGH net: nfc: nci: Fix parameter validation for packet data
CVE-2026-43365 8.2 HIGH xfs: fix undersized l_iclog_roundoff values
CVE-2026-43466 8.2 HIGH net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery

Showing top 20 of 197 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43315

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