CVE-2026-64307
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: crypto: ccp - Do not initialize SNP for ioctl(SNP_CONFIG) Sashiko notes: > if SEV initialization fails and KVM is actively running normal VMs, could a > userspace process trigger this code path via /dev/sev ioctls (e.g., > SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN > execution for an active VM trigger a general protection fault and crash the > host? Refuse to re-try initialization if SNP is not already initialized for SNP_CONFIG. This is technically an ABI break: before if SNP initialization failed it could be transparently retriggered by this ioctl, and if no VMs were running, everything worked fine. Hopefully this is enough of a corner case that nobody will notice, but someone does, there are a few options: * do something like symbol_get() for kvm and refuse to initialize if KVM is loaded * check each cpu's HSAVE_PA for non-zero data before re-initializing * once initialization has failed, continue to refuse to initialize until the ccp module is unloaded
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-07-25 10:17:11.800000
Last modified
2026-10-24 13:10:00.147000
View original CVE JSON
{
"id": "CVE-2026-64307",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-07-25T10:17:11.800",
"lastModified": "2026-10-24T13:10:00.147",
"vulnStatus": "Analyzed",
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: ccp - Do not initialize SNP for ioctl(SNP_CONFIG)\n\nSashiko notes:\n\n> if SEV initialization fails and KVM is actively running normal VMs, could a\n> userspace process trigger this code path via /dev/sev ioctls (e.g.,\n> SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN\n> execution for an active VM trigger a general protection fault and crash the\n> host?\n\nRefuse to re-try initialization if SNP is not already initialized for\nSNP_CONFIG.\n\nThis is technically an ABI break: before if SNP initialization failed it\ncould be transparently retriggered by this ioctl, and if no VMs were\nrunning, everything worked fine. Hopefully this is enough of a corner case\nthat nobody will notice, but someone does, there are a few options:\n\n* do something like symbol_get() for kvm and refuse to initialize if KVM is\n loaded\n* check each cpu's HSAVE_PA for non-zero data before re-initializing\n* once initialization has failed, continue to refuse to initialize until\n the ccp module is unloaded"
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ncrypto: ccp - No inicializar SNP para ioctl(SNP_CONFIG)\n\nNotas de Sashiko:\n\n> si la inicialización de SEV falla y KVM está ejecutando activamente máquinas virtuales normales, ¿podría un proceso de espacio de usuario activar esta ruta de código a través de ioctls de /dev/sev (p. ej., SEV_PDH_GEN) y poner a cero MSR_VM_HSAVE_PA globalmente? ¿La siguiente ejecución de VMRUN para una máquina virtual activa desencadenaría una falla de protección general y bloquearía el host?\n\nRechazar reintentar la inicialización si SNP no está ya inicializado para SNP_CONFIG.\n\nEsto es técnicamente una ruptura de ABI: antes, si la inicialización de SNP fallaba, podía ser re-activada transparentemente por este ioctl, y si no había máquinas virtuales en ejecución, todo funcionaba bien. Con suerte, este es un caso tan excepcional que nadie lo notará, pero si alguien lo hace, hay algunas opciones:\n\n* hacer algo como symbol_get() para kvm y negarse a inicializar si KVM está cargado\n* verificar el HSAVE_PA de cada CPU en busca de datos no nulos antes de reinicializar\n* una vez que la inicialización ha fallado, continuar negándose a inicializar hasta que el módulo ccp sea descargado"
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"privilegesRequired": "LOW",
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"scope": "UNCHANGED",
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"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
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