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NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.13% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 155ec243ef726f4bc49536fa0bfb565dc011ab17, 580ea57840864d40e019bc13fd26afdc8d510a2f, 969e5e13ff5c18603f21d1f9f64ec9194e141ac0.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 155ec243ef726f4bc49536fa0bfb565dc011ab17, 580ea57840864d40e019bc13fd26afdc8d510a2f, 969e5e13ff5c18603f21d1f9f64ec9194e141ac0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 8, 2026
Updated
Jun 17, 2026
EPSS
0.1% · 2th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.14 and later · before 5.15.202
  • linux linux kernel5.16 and later · before 6.1.165
  • linux linux kernel6.2 and later · before 6.6.128
  • linux linux kernel6.7 and later · before 6.12.75
  • linux linux kernel6.13 and later · before 6.18.16
  • linux linux kernel6.19 and later · before 6.19.6

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.14affected
    • b222b0b88162bdef4eceb12a79d5edbbdb23dbfd and later · before 155ec243ef726f4bc49536fa0bfb565dc011ab17affected · git
    • b222b0b88162bdef4eceb12a79d5edbbdb23dbfd and later · before 580ea57840864d40e019bc13fd26afdc8d510a2faffected · git
    • b222b0b88162bdef4eceb12a79d5edbbdb23dbfd and later · before deb8f6dfd31d94b18dbeeaa8c01fbec5fc70fd2baffected · git
    • b222b0b88162bdef4eceb12a79d5edbbdb23dbfd and later · before ce904c8a5bbe697eae0f7e34b07095bd7a6dee19affected · git
    • b222b0b88162bdef4eceb12a79d5edbbdb23dbfd and later · before 969e5e13ff5c18603f21d1f9f64ec9194e141ac0affected · git
    • b222b0b88162bdef4eceb12a79d5edbbdb23dbfd and later · before ebb2ab4f1c87d6b52776292cf7dc16aea48e95f8affected · git
    • b222b0b88162bdef4eceb12a79d5edbbdb23dbfd and later · before fc3ba56385d03501eb582e4b86691ba378e556f9affected · git
    • before 5.14not affected · semver
    • 5.15.202 and later · up to and including 5.15.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.6-16.19.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-43313May 8, 2026 · ACPI: processor: Fix NULL-pointer dereference in acpi_processor_errata_piix4()
    22Monitor
  • ← EarlierCVE-2026-43314May 8, 2026 · dm: remove fake timeout to avoid leak request
    22Monitor
  • Later →CVE-2026-43316May 8, 2026 · media: solo6x10: Check for out of bounds chip_id
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux155ec243ef726f4bc49536fa0bfb565dc011ab17Vendor (CNA)
Linux Linux580ea57840864d40e019bc13fd26afdc8d510a2fVendor (CNA)
Linux Linux969e5e13ff5c18603f21d1f9f64ec9194e141ac0Vendor (CNA)
Linux Linuxce904c8a5bbe697eae0f7e34b07095bd7a6dee19Vendor (CNA)
Linux Linuxdeb8f6dfd31d94b18dbeeaa8c01fbec5fc70fd2bVendor (CNA)
Linux Linuxebb2ab4f1c87d6b52776292cf7dc16aea48e95f8Vendor (CNA)
Linux Linuxfc3ba56385d03501eb582e4b86691ba378e556f9Vendor (CNA)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records