CVE-2026-31593 (GCVE-0-2026-31593)
Vulnerability from cvelistv5 – Published: 2026-04-24 14:42 – Updated: 2026-06-14 17:42
VLAI
EPSS
VEX
Title
KVM: SEV: Reject attempts to sync VMSA of an already-launched/encrypted vCPU
Summary
In the Linux kernel, the following vulnerability has been resolved:
KVM: SEV: Reject attempts to sync VMSA of an already-launched/encrypted vCPU
Reject synchronizing vCPU state to its associated VMSA if the vCPU has
already been launched, i.e. if the VMSA has already been encrypted. On a
host with SNP enabled, accessing guest-private memory generates an RMP #PF
and panics the host.
BUG: unable to handle page fault for address: ff1276cbfdf36000
#PF: supervisor write access in kernel mode
#PF: error_code(0x80000003) - RMP violation
PGD 5a31801067 P4D 5a31802067 PUD 40ccfb5063 PMD 40e5954063 PTE 80000040fdf36163
SEV-SNP: PFN 0x40fdf36, RMP entry: [0x6010fffffffff001 - 0x000000000000001f]
Oops: Oops: 0003 [#1] SMP NOPTI
CPU: 33 UID: 0 PID: 996180 Comm: qemu-system-x86 Tainted: G OE
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: Dell Inc. PowerEdge R7625/0H1TJT, BIOS 1.5.8 07/21/2023
RIP: 0010:sev_es_sync_vmsa+0x54/0x4c0 [kvm_amd]
Call Trace:
<TASK>
snp_launch_update_vmsa+0x19d/0x290 [kvm_amd]
snp_launch_finish+0xb6/0x380 [kvm_amd]
sev_mem_enc_ioctl+0x14e/0x720 [kvm_amd]
kvm_arch_vm_ioctl+0x837/0xcf0 [kvm]
kvm_vm_ioctl+0x3fd/0xcc0 [kvm]
__x64_sys_ioctl+0xa3/0x100
x64_sys_call+0xfe0/0x2350
do_syscall_64+0x81/0x10f0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7ffff673287d
</TASK>
Note, the KVM flaw has been present since commit ad73109ae7ec ("KVM: SVM:
Provide support to launch and run an SEV-ES guest"), but has only been
actively dangerous for the host since SNP support was added. With SEV-ES,
KVM would "just" clobber guest state, which is totally fine from a host
kernel perspective since userspace can clobber guest state any time before
sev_launch_update_vmsa().
Severity
5.5 (Medium)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
ad27ce155566f2b4400fa865859834592bd18777 , < c9609847ae65ca36233077c2b6cb2bc0fb37c77a
(git)
Affected: ad27ce155566f2b4400fa865859834592bd18777 , < 692fdf05e55fa03960a1278afdc2478c12daea13 (git) Affected: ad27ce155566f2b4400fa865859834592bd18777 , < 6ef109e01e1d35199e1a97ea68bdfd3cf3fbf9ab (git) Affected: ad27ce155566f2b4400fa865859834592bd18777 , < 8f85a4885eee8cb495961ffa371a91828afb9445 (git) Affected: ad27ce155566f2b4400fa865859834592bd18777 , < 9b9f7962e3e879d12da2bf47e02a24ec51690e3d (git) |
guessed | |
| Linux | Linux |
Affected:
6.11
Unaffected: 0 , < 6.11 (semver) Unaffected: 6.12.83 , ≤ 6.12.* (semver) Unaffected: 6.18.24 , ≤ 6.18.* (semver) Unaffected: 6.19.14 , ≤ 6.19.* (semver) Unaffected: 7.0.1 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix) |
guessed |
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}
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{
"url": "https://git.kernel.org/stable/c/9b9f7962e3e879d12da2bf47e02a24ec51690e3d"
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Reject attempts to sync VMSA of an already-launched/encrypted vCPU\n\nReject synchronizing vCPU state to its associated VMSA if the vCPU has\nalready been launched, i.e. if the VMSA has already been encrypted. On a\nhost with SNP enabled, accessing guest-private memory generates an RMP #PF\nand panics the host.\n\n BUG: unable to handle page fault for address: ff1276cbfdf36000\n #PF: supervisor write access in kernel mode\n #PF: error_code(0x80000003) - RMP violation\n PGD 5a31801067 P4D 5a31802067 PUD 40ccfb5063 PMD 40e5954063 PTE 80000040fdf36163\n SEV-SNP: PFN 0x40fdf36, RMP entry: [0x6010fffffffff001 - 0x000000000000001f]\n Oops: Oops: 0003 [#1] SMP NOPTI\n CPU: 33 UID: 0 PID: 996180 Comm: qemu-system-x86 Tainted: G OE\n Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE\n Hardware name: Dell Inc. PowerEdge R7625/0H1TJT, BIOS 1.5.8 07/21/2023\n RIP: 0010:sev_es_sync_vmsa+0x54/0x4c0 [kvm_amd]\n Call Trace:\n \u003cTASK\u003e\n snp_launch_update_vmsa+0x19d/0x290 [kvm_amd]\n snp_launch_finish+0xb6/0x380 [kvm_amd]\n sev_mem_enc_ioctl+0x14e/0x720 [kvm_amd]\n kvm_arch_vm_ioctl+0x837/0xcf0 [kvm]\n kvm_vm_ioctl+0x3fd/0xcc0 [kvm]\n __x64_sys_ioctl+0xa3/0x100\n x64_sys_call+0xfe0/0x2350\n do_syscall_64+0x81/0x10f0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n RIP: 0033:0x7ffff673287d\n \u003c/TASK\u003e\n\nNote, the KVM flaw has been present since commit ad73109ae7ec (\"KVM: SVM:\nProvide support to launch and run an SEV-ES guest\"), but has only been\nactively dangerous for the host since SNP support was added. With SEV-ES,\nKVM would \"just\" clobber guest state, which is totally fine from a host\nkernel perspective since userspace can clobber guest state any time before\nsev_launch_update_vmsa()."
}
],
"id": "CVE-2026-31593",
"lastModified": "2026-06-17T10:34:02.900",
"metrics": {
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"availabilityImpact": "HIGH",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
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"source": "nvd@nist.gov",
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}
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},
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"vulnStatus": "Analyzed",
"weaknesses": [
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"value": "NVD-CWE-noinfo"
}
],
"source": "nvd@nist.gov",
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},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-06-28T07:26:42+00:00",
"cve": "CVE-2026-31593",
"id": "CVE-2026-31593",
"initial_release_date": "2026-04-24T00:00:00+00:00",
"product_status:known_affected": "260",
"product_status:known_not_affected": "14",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: KVM: SEV: Reject attempts to sync VMSA of an already-launched/encrypted vCPU",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31593.json",
"version": "3"
}
}
}
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Nomenclature
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.