CVE-2026-98745
En el kernel de Linux se ha resuelto la siguiente vulnerabilidad:
arm64/fpsimd: signal: Forbid non-streaming SVE payload on SME-only systems
Cuando system_supports_sme() es verdadero pero system_supports_sve() es falso, restaurar un contexto de señal SVE especialmente diseñado puede provocar que la tarea tenga erróneamente un estado SVE no streaming. Los intentos posteriores de manipular el estado FPSIMD/SVE/SME de la tarea pueden dar lugar a diversos problemas, incluidos UNDEF fatales en EL1.
En estas configuraciones, el kernel siempre crea un contexto de señal SVE al entregar una señal, y este solo puede estar en uno de dos estados:
Leer descripción completaMostrar menos
(1) SVE_SIG_FLAG_SM está activado y hay una carga útil SVE que contiene el estado SVE en modo streaming. El VL registrado es el VL de streaming activo de la tarea.
(2) SVE_SIG_FLAG_SM está desactivado y no hay carga útil SVE. El contexto FPSIMD contiene el estado FPSIMD en modo no streaming. El VL registrado es 0.
Actualmente, restore_sve_fpsimd_context() rechaza correctamente los casos en que SVE_SIG_FLAG_SM está activado y no hay carga útil SVE, pero no rechaza los casos en que SVE_SIG_FLAG_SM está desactivado y sí hay carga útil SVE. En consecuencia, restore_sve_fpsimd_context() puede dejar la tarea en un estado con estado SVE no streaming incluso cuando el hardware no lo admite.
Por ejemplo, esto puede provocar un UNDEF posterior en EL1 cuando el kernel intenta restaurar el valor ZCR_EL1 de la tarea:
| # ./sme-sigcontext-to-sve | Internal error: Oops - Undefined instruction: 0000000002000000 [#1] SMP | Modules linked in: | CPU: 0 UID: 0 PID: 131 Comm: sme-sigcontext- Not tainted 7.3.0-rc1 #1 PREEMPT | Hardware name: linux,dummy-virt (DT) | pstate: 61402009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) | pc : fpsimd_restore_current_state+0x258/0x458 | lr : exit_to_user_mode_loop+0xb8/0x188 | sp : ffff80008056be40 | x29: ffff80008056be40 x28: fff00000c1670000 x27: 0000000000000000 | x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 | x23: ffff80008056bec0 x22: 0000000000000008 x21: 0000000000000040 | x20: 0000000000000081 x19: 0000000008800010 x18: 0000000000000000 | x17: 0000fffffd412570 x16: 0000000000001000 x15: 0000fffffd4123b0 | x14: 0000fffffd412780 x13: 0000fffffd412be8 x12: 0000000047435300 | x11: 0000fffffd412570 x10: 0000000000000000 x9 : 0000000045585401 | x8 : fff00000c18a6c44 x7 : 0000000000000000 x6 : 0000000000000002 | x5 : 0000000000000002 x4 : ffff800080568000 x3 : 0000000000000001 | x2 : 0000000008800010 x1 : fff00000c1670000 x0 : 0000000008800000 | Call trace: | fpsimd_restore_current_state+0x258/0x458 (P) | exit_to_user_mode_loop+0xb8/0x188 | el0_svc+0x1cc/0x1d0 | el0t_64_sync_handler+0xa0/0xe4 | el0t_64_sync+0x198/0x19c | Code: d5384101 f9400020 53175c03 36b80de0 (d5381202) | ---[ end trace 0000000000000000 ]--- | Kernel panic - not syncing: Oops - Undefined instruction: Fatal exception in interrupt | Kernel Offset: 0x291fb1000000 from 0xffff800080000000 | PHYS_OFFSET: 0x40000000 | CPU features: 0x0,00000000,0052802f,ffb88f43,3afcf73f | Memory Limit: none
Rehacer restore_sve_fpsimd_context() para rechazar los casos en que SVE_SIG_FLAG_SM está desactivado y no hay carga útil SVE. Como parse_user_sigframe() rechaza los marcos de señal SVE cuando no se admiten ni SVE ni SME, no es necesario que restore_sve_fpsimd_context() gestione el caso en que no se admite ninguno de los dos.
Traducción automática del texto original de NVD (en inglés).
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días
- 0.17 %
- Percentil entre todas las CVEs puntuadas
- 6
- Fecha de la puntuación
- 20/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
Mostrar las 4 referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-98745",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
"lessThan": "f2338929c7663859c0c74dd6fef2c0245066f845",
"versionType": "git"
},
{
"status": "affected",
"version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
"lessThan": "2bce6f006cfe0b60e8249fd8d51396d99355cba3",
"versionType": "git"
},
{
"status": "affected",
"version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
"lessThan": "88c1c611552b24658eb61244086691c02be2013b",
"versionType": "git"
},
{
"status": "affected",
"version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033",
"lessThan": "e060d9069b49fe55f38057dfe592068014652671",
"versionType": "git"
},
{
"status": "affected",
"version": "05458ee3ff82b31a4564836a84ef20d6c233dfc7",
"versionType": "git"
},
{
"status": "affected",
"version": "6.1.7",
"lessThan": "6.2",
"versionType": "semver"
}
],
"programFiles": [
"arch/arm64/kernel/signal.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.2"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.113",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.56",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/arm64/kernel/signal.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:17:28.237",
"references": [
{
"url": "https://git.kernel.org/stable/c/2bce6f006cfe0b60e8249fd8d51396d99355cba3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/88c1c611552b24658eb61244086691c02be2013b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e060d9069b49fe55f38057dfe592068014652671",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f2338929c7663859c0c74dd6fef2c0245066f845",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64/fpsimd: signal: Forbid non-streaming SVE payload on SME-only systems\n\nWhen system_supports_sme() is true but system_supports_sve() is false,\nrestoring a specifically crafted SVE signal context can result in the\ntask erroneously having non-streaming SVE state. Subsequent attempts to\nmanipulate the task's FPSIMD/SVE/SME state can result in a variety of\nproblems, including fatal EL1 UNDEFs.\n\nIn such configurations, the kernel always creates an SVE signal context\nwhen delivering a signal, and this can only be in one of two states:\n\n(1) SVE_SIG_FLAG_SM is set, and an SVE payload is present containing\n streaming mode SVE state. The recorded VL is the task's live\n streaming VL.\n\n(2) SVE_SIG_FLAG_SM is clear, and an SVE payload is not present. The\n FPSIMD context contains the non-streaming mode FPSIMD state. The\n recorded VL is 0.\n\nCurrently restore_sve_fpsimd_context() correctly rejects cases where\nSVE_SIG_FLAG_SM is set and an SVE payload is not present, but fails to\nreject cases where SVE_SIG_FLAG_SM is clear and an SVE payload is\npresent. Consequently, restore_sve_fpsimd_context() can place the task\nin a state where it has non-streaming SVE state even when this is not\nsupported by HW.\n\nFor example, this can cause a later EL1 UNDEF when the kernel attempts to\nrestore the task's ZCR_EL1 value:\n\n| # ./sme-sigcontext-to-sve\n| Internal error: Oops - Undefined instruction: 0000000002000000 [#1] SMP\n| Modules linked in:\n| CPU: 0 UID: 0 PID: 131 Comm: sme-sigcontext- Not tainted 7.3.0-rc1 #1 PREEMPT\n| Hardware name: linux,dummy-virt (DT)\n| pstate: 61402009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)\n| pc : fpsimd_restore_current_state+0x258/0x458\n| lr : exit_to_user_mode_loop+0xb8/0x188\n| sp : ffff80008056be40\n| x29: ffff80008056be40 x28: fff00000c1670000 x27: 0000000000000000\n| x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000\n| x23: ffff80008056bec0 x22: 0000000000000008 x21: 0000000000000040\n| x20: 0000000000000081 x19: 0000000008800010 x18: 0000000000000000\n| x17: 0000fffffd412570 x16: 0000000000001000 x15: 0000fffffd4123b0\n| x14: 0000fffffd412780 x13: 0000fffffd412be8 x12: 0000000047435300\n| x11: 0000fffffd412570 x10: 0000000000000000 x9 : 0000000045585401\n| x8 : fff00000c18a6c44 x7 : 0000000000000000 x6 : 0000000000000002\n| x5 : 0000000000000002 x4 : ffff800080568000 x3 : 0000000000000001\n| x2 : 0000000008800010 x1 : fff00000c1670000 x0 : 0000000008800000\n| Call trace:\n| fpsimd_restore_current_state+0x258/0x458 (P)\n| exit_to_user_mode_loop+0xb8/0x188\n| el0_svc+0x1cc/0x1d0\n| el0t_64_sync_handler+0xa0/0xe4\n| el0t_64_sync+0x198/0x19c\n| Code: d5384101 f9400020 53175c03 36b80de0 (d5381202)\n| ---[ end trace 0000000000000000 ]---\n| Kernel panic - not syncing: Oops - Undefined instruction: Fatal exception in interrupt\n| Kernel Offset: 0x291fb1000000 from 0xffff800080000000\n| PHYS_OFFSET: 0x40000000\n| CPU features: 0x0,00000000,0052802f,ffb88f43,3afcf73f\n| Memory Limit: none\n\nRework restore_sve_fpsimd_context() to reject cases where\nSVE_SIG_FLAG_SM is clear and an SVE payload is not present. As\nparse_user_sigframe() rejects SVE signal frames when neither SVE nor SME\nare supported, it isn't necessary for restore_sve_fpsimd_context() to\nhandle the case where neither are supported."
}
],
"lastModified": "2026-10-19T10:19:38.670",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}