CVE-2026-97937
In the Linux kernel, the following vulnerability has been resolved:
ftrace: fork: Initialize function graph state before copy_exec_state()
dup_task_struct() copies the parent's task_struct, including ret_stack. ftrace_graph_init_task() clears the copied function graph state, but it currently runs after copy_exec_state().
For non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state. If that allocation fails, copy_process() reaches bad_fork_free and free_task() calls ftrace_graph_exit_task(). Since the child still carries the parent's ret_stack pointer, the unwind frees the parent's active function graph return stack. The parent subsequently accesses freed memory from function_graph_enter_regs().
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Initialize the child function graph state immediately after dup_task_struct(), before the first fallible operation.
Detalles técnicos trazas, registros y código del informe original
KASAN reports: [ 22.190920] ================================================================== [ 22.195899] BUG: KASAN: slab-use-after-free in function_graph_enter_regs+0xa76/0xb90 [ 22.200747] Write of size 8 at addr ff110000054dc0a8 by task repro/1 [ 22.205134] [ 22.210770] CPU: 0 UID: 0 PID: 1 Comm: repro Not tainted 7.2.0-07732-g9328b3b03bdc-dirty #3 PREEMPT(lazy) [ 22.212576] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 22.213750] Call Trace: [ 22.215271] <TASK> [ 22.216242] ? ftrace_stub_direct_tramp+0x10/0x10 [ 22.217774] dump_stack_lvl+0x4e/0x70 [ 22.220531] print_report+0x157/0x4b4 [ 22.223202] ? fixup_red_left+0x9/0x30 [ 22.224407] ? complete_report_info+0x83/0x110 [ 22.226679] ? function_graph_enter_regs+0xa76/0xb90 [ 22.228084] kasan_report+0xce/0x100 [ 22.230109] ? function_graph_enter_regs+0xa76/0xb90 [ 22.232860] ? stack_trace_save+0x4/0xd0 [ 22.234156] function_graph_enter_regs+0xa76/0xb90 [ 22.236090] ? kasan_save_stack+0x30/0x50 [ 22.237752] ? __pfx_function_graph_enter_regs+0x10/0x10 [ 22.238694] ? ring_buffer_lock_reserve+0x345/0xf80 [ 22.239628] ? stack_trace_save+0x4/0xd0 [ 22.242121] ? stack_trace_save+0x4/0xd0 [ 22.243588] ftrace_graph_func+0xda/0x160 [ 22.245362] ? ftrace_stub_direct_tramp+0x10/0x10 [ 22.246520] 0xffffffffa0000095 [ 22.250528] ? stack_trace_save+0x9/0xd0 [ 22.251757] ? ring_buffer_unlock_commit+0x11d/0x5c0 [ 22.253152] stack_trace_save+0x9/0xd0 [ 22.254264] kasan_save_stack+0x30/0x50 [ 22.273631] kasan_save_track+0x14/0x30 [ 22.276763] kasan_save_free_info+0x3b/0x70 [ 22.278296] __kasan_slab_free+0x43/0x70 [ 22.280157] kmem_cache_free+0xbf/0x3b0 [ 22.282963] ? ftrace_stub_direct_tramp+0x10/0x10 [ 22.284001] free_task+0xa2/0x160 [ 22.285699] ? ftrace_stub_direct_tramp+0x10/0x10 [ 22.286752] copy_process+0x2aae/0x7bc0
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.15%
- Percentil entre todas las CVEs puntuadas: 4
- Fecha de la puntuación: 6/10/2026
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).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1005Data from Local Systemcollection75 % - Impacto secundario
T1499.004Application or System Exploitationimpact70 %
Vulnerabilidad local (AV:L/PR:L) que permite use-after-free al manipular el estado de fork en el kernel; permite lectura de memoria liberada (KASAN) y potencial DoS por corrupción de memoria.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-97937",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.8,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 1.8
}
]
},
"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": "6b1c66c9cca99bf00386481c7b2aa7394c26d8b8",
"lessThan": "1fadebbbf31f65beba353fa9d1373bf183e03fed",
"versionType": "git"
},
{
"status": "affected",
"version": "6b1c66c9cca99bf00386481c7b2aa7394c26d8b8",
"lessThan": "08cacffeef8f64f1a222c93467ca84f24a46c953",
"versionType": "git"
}
],
"programFiles": [
"kernel/fork.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7.2"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "7.2.7",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/fork.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-25T11:17:21.080",
"references": [
{
"url": "https://git.kernel.org/stable/c/08cacffeef8f64f1a222c93467ca84f24a46c953",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/1fadebbbf31f65beba353fa9d1373bf183e03fed",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nftrace: fork: Initialize function graph state before copy_exec_state()\n\ndup_task_struct() copies the parent's task_struct, including ret_stack.\nftrace_graph_init_task() clears the copied function graph state, but it\ncurrently runs after copy_exec_state().\n\nFor non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state.\nIf that allocation fails, copy_process() reaches bad_fork_free and\nfree_task() calls ftrace_graph_exit_task(). Since the child still carries\nthe parent's ret_stack pointer, the unwind frees the parent's active\nfunction graph return stack. The parent subsequently accesses freed memory\nfrom function_graph_enter_regs().\n\nKASAN reports:\n\n[ 22.190920] ==================================================================\n[ 22.195899] BUG: KASAN: slab-use-after-free in function_graph_enter_regs+0xa76/0xb90\n[ 22.200747] Write of size 8 at addr ff110000054dc0a8 by task repro/1\n[ 22.205134]\n[ 22.210770] CPU: 0 UID: 0 PID: 1 Comm: repro Not tainted 7.2.0-07732-g9328b3b03bdc-dirty #3 PREEMPT(lazy)\n[ 22.212576] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n[ 22.213750] Call Trace:\n[ 22.215271] <TASK>\n[ 22.216242] ? ftrace_stub_direct_tramp+0x10/0x10\n[ 22.217774] dump_stack_lvl+0x4e/0x70\n[ 22.220531] print_report+0x157/0x4b4\n[ 22.223202] ? fixup_red_left+0x9/0x30\n[ 22.224407] ? complete_report_info+0x83/0x110\n[ 22.226679] ? function_graph_enter_regs+0xa76/0xb90\n[ 22.228084] kasan_report+0xce/0x100\n[ 22.230109] ? function_graph_enter_regs+0xa76/0xb90\n[ 22.232860] ? stack_trace_save+0x4/0xd0\n[ 22.234156] function_graph_enter_regs+0xa76/0xb90\n[ 22.236090] ? kasan_save_stack+0x30/0x50\n[ 22.237752] ? __pfx_function_graph_enter_regs+0x10/0x10\n[ 22.238694] ? ring_buffer_lock_reserve+0x345/0xf80\n[ 22.239628] ? stack_trace_save+0x4/0xd0\n[ 22.242121] ? stack_trace_save+0x4/0xd0\n[ 22.243588] ftrace_graph_func+0xda/0x160\n[ 22.245362] ? ftrace_stub_direct_tramp+0x10/0x10\n[ 22.246520] 0xffffffffa0000095\n[ 22.250528] ? stack_trace_save+0x9/0xd0\n[ 22.251757] ? ring_buffer_unlock_commit+0x11d/0x5c0\n[ 22.253152] stack_trace_save+0x9/0xd0\n[ 22.254264] kasan_save_stack+0x30/0x50\n[ 22.273631] kasan_save_track+0x14/0x30\n[ 22.276763] kasan_save_free_info+0x3b/0x70\n[ 22.278296] __kasan_slab_free+0x43/0x70\n[ 22.280157] kmem_cache_free+0xbf/0x3b0\n[ 22.282963] ? ftrace_stub_direct_tramp+0x10/0x10\n[ 22.284001] free_task+0xa2/0x160\n[ 22.285699] ? ftrace_stub_direct_tramp+0x10/0x10\n[ 22.286752] copy_process+0x2aae/0x7bc0\n\nInitialize the child function graph state immediately after\ndup_task_struct(), before the first fallible operation."
}
],
"lastModified": "2026-09-25T15:18:02.577",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}