CVE-2025-39776
Estado: ModificadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
mm/debug_vm_pgtable: clear page table entries at destroy_args()
The mm/debug_vm_pagetable test allocates manually page table entries for the tests it runs, using also its manually allocated mm_struct. That in itself is ok, but when it exits, at destroy_args() it fails to clear those entries with the *_clear functions.
The problem is that leaves stale entries. If another process allocates an mm_struct with a pgd at the same address, it may end up running into the stale entry.
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This is happening in practice on a debug kernel with CONFIG_DEBUG_VM_PGTABLE=y, for example this is the output with some extra debugging I added (it prints a warning trace if pgtables_bytes goes negative, in addition to the warning at check_mm() function):
Here the modprobe process ended up with an allocated mm_struct from the mm_struct slab that was used before by the debug_vm_pgtable test. That is not a problem, since the mm_stru ---truncated---
Detalles técnicos trazas, registros y código del informe original
[ 2.539353] debug_vm_pgtable: [get_random_vaddr ]: random_vaddr is 0x7ea247140000 [ 2.539366] kmem_cache info [ 2.539374] kmem_cachep 0x000000002ce82385 - freelist 0x0000000000000000 - offset 0x508 [ 2.539447] debug_vm_pgtable: [init_args ]: args->mm is 0x000000002267cc9e (...) [ 2.552800] WARNING: CPU: 5 PID: 116 at include/linux/mm.h:2841 free_pud_range+0x8bc/0x8d0 [ 2.552816] Modules linked in: [ 2.552843] CPU: 5 UID: 0 PID: 116 Comm: modprobe Not tainted 6.12.0-105.debug_vm2.el10.ppc64le+debug #1 VOLUNTARY [ 2.552859] Hardware name: IBM,9009-41A POWER9 (architected) 0x4e0202 0xf000005 of:IBM,FW910.00 (VL910_062) hv:phyp pSeries [ 2.552872] NIP: c0000000007eef3c LR: c0000000007eef30 CTR: c0000000003d8c90 [ 2.552885] REGS: c0000000622e73b0 TRAP: 0700 Not tainted (6.12.0-105.debug_vm2.el10.ppc64le+debug) [ 2.552899] MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24002822 XER: 0000000a [ 2.552954] CFAR: c0000000008f03f0 IRQMASK: 0 [ 2.552954] GPR00: c0000000007eef30 c0000000622e7650 c000000002b1ac00 0000000000000001 [ 2.552954] GPR04: 0000000000000008 0000000000000000 c0000000007eef30 ffffffffffffffff [ 2.552954] GPR08: 00000000ffff00f5 0000000000000001 0000000000000048 0000000000004000 [ 2.552954] GPR12: 00000003fa440000 c000000017ffa300 c0000000051d9f80 ffffffffffffffdb [ 2.552954] GPR16: 0000000000000000 0000000000000008 000000000000000a 60000000000000e0 [ 2.552954] GPR20: 4080000000000000 c0000000113af038 00007fffcf130000 0000700000000000 [ 2.552954] GPR24: c000000062a6a000 0000000000000001 8000000062a68000 0000000000000001 [ 2.552954] GPR28: 000000000000000a c000000062ebc600 0000000000002000 c000000062ebc760 [ 2.553170] NIP [c0000000007eef3c] free_pud_range+0x8bc/0x8d0 [ 2.553185] LR [c0000000007eef30] free_pud_range+0x8b0/0x8d0 [ 2.553199] Call Trace: [ 2.553207] [c0000000622e7650] [c0000000007eef30] free_pud_range+0x8b0/0x8d0 (unreliable) [ 2.553229] [c0000000622e7750] [c0000000007f40b4] free_pgd_range+0x284/0x3b0 [ 2.553248] [c0000000622e7800] [c0000000007f4630] free_pgtables+0x450/0x570 [ 2.553274] [c0000000622e78e0] [c0000000008161c0] exit_mmap+0x250/0x650 [ 2.553292] [c0000000622e7a30] [c0000000001b95b8] __mmput+0x98/0x290 [ 2.558344] [c0000000622e7a80] [c0000000001d1018] exit_mm+0x118/0x1b0 [ 2.558361] [c0000000622e7ac0] [c0000000001d141c] do_exit+0x2ec/0x870 [ 2.558376] [c0000000622e7b60] [c0000000001d1ca8] do_group_exit+0x88/0x150 [ 2.558391] [c0000000622e7bb0] [c0000000001d1db8] sys_exit_group+0x48/0x50 [ 2.558407] [c0000000622e7be0] [c00000000003d810] system_call_exception+0x1e0/0x4c0 [ 2.558423] [c0000000622e7e50] [c00000000000d05c] system_call_vectored_common+0x15c/0x2ec (...) [ 2.558892] ---[ end trace 0000000000000000 ]--- [ 2.559022] BUG: Bad rss-counter state mm:000000002267cc9e type:MM_ANONPAGES val:1 [ 2.559037] BUG: non-zero pgtables_bytes on freeing mm: -6144
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
T1059Command and Scripting Interpreterexecution75 % - Impacto secundario
T1498.002Reflection Amplificationimpact60 %
Vulnerabilidad local (AV:L/PR:L) que deja entradas de tabla de páginas sin limpiar, permitiendo escalada de privilegios o ejecución de código cuando otro proceso reutiliza la misma estructura de memoria. CWE-416 (use-after-free) en kernel facilita compromiso de seguridad del sistema.
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 (2)
CWE
- CWE-416
Referencias
- https://git.kernel.org/stable/c/47d2a149611b8a94d24add9868c442a4af278658
- https://git.kernel.org/stable/c/561171db3b3eb759ba3f284dba7a76f4476ade03
- https://git.kernel.org/stable/c/61a9f2e5c49f05e3ea2c16674540a075a1b4be6f
- https://git.kernel.org/stable/c/63962ff932ef359925b94be2a88df6b4fd4fed0a
- https://git.kernel.org/stable/c/7bf57a0709cd7c9088cea8de023d6f4fbf2518b0
- https://git.kernel.org/stable/c/dde30854bddfb5d69f30022b53c5955a41088b33
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
JSON original (NVD)
Mostrar
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"published": "2025-09-11T17:15:43.457",
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"weaknesses": [
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"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "CWE-416"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/debug_vm_pgtable: clear page table entries at destroy_args()\n\nThe mm/debug_vm_pagetable test allocates manually page table entries for\nthe tests it runs, using also its manually allocated mm_struct. That in\nitself is ok, but when it exits, at destroy_args() it fails to clear those\nentries with the *_clear functions.\n\nThe problem is that leaves stale entries. If another process allocates an\nmm_struct with a pgd at the same address, it may end up running into the\nstale entry. This is happening in practice on a debug kernel with\nCONFIG_DEBUG_VM_PGTABLE=y, for example this is the output with some extra\ndebugging I added (it prints a warning trace if pgtables_bytes goes\nnegative, in addition to the warning at check_mm() function):\n\n[ 2.539353] debug_vm_pgtable: [get_random_vaddr ]: random_vaddr is 0x7ea247140000\n[ 2.539366] kmem_cache info\n[ 2.539374] kmem_cachep 0x000000002ce82385 - freelist 0x0000000000000000 - offset 0x508\n[ 2.539447] debug_vm_pgtable: [init_args ]: args->mm is 0x000000002267cc9e\n(...)\n[ 2.552800] WARNING: CPU: 5 PID: 116 at include/linux/mm.h:2841 free_pud_range+0x8bc/0x8d0\n[ 2.552816] Modules linked in:\n[ 2.552843] CPU: 5 UID: 0 PID: 116 Comm: modprobe Not tainted 6.12.0-105.debug_vm2.el10.ppc64le+debug #1 VOLUNTARY\n[ 2.552859] Hardware name: IBM,9009-41A POWER9 (architected) 0x4e0202 0xf000005 of:IBM,FW910.00 (VL910_062) hv:phyp pSeries\n[ 2.552872] NIP: c0000000007eef3c LR: c0000000007eef30 CTR: c0000000003d8c90\n[ 2.552885] REGS: c0000000622e73b0 TRAP: 0700 Not tainted (6.12.0-105.debug_vm2.el10.ppc64le+debug)\n[ 2.552899] MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24002822 XER: 0000000a\n[ 2.552954] CFAR: c0000000008f03f0 IRQMASK: 0\n[ 2.552954] GPR00: c0000000007eef30 c0000000622e7650 c000000002b1ac00 0000000000000001\n[ 2.552954] GPR04: 0000000000000008 0000000000000000 c0000000007eef30 ffffffffffffffff\n[ 2.552954] GPR08: 00000000ffff00f5 0000000000000001 0000000000000048 0000000000004000\n[ 2.552954] GPR12: 00000003fa440000 c000000017ffa300 c0000000051d9f80 ffffffffffffffdb\n[ 2.552954] GPR16: 0000000000000000 0000000000000008 000000000000000a 60000000000000e0\n[ 2.552954] GPR20: 4080000000000000 c0000000113af038 00007fffcf130000 0000700000000000\n[ 2.552954] GPR24: c000000062a6a000 0000000000000001 8000000062a68000 0000000000000001\n[ 2.552954] GPR28: 000000000000000a c000000062ebc600 0000000000002000 c000000062ebc760\n[ 2.553170] NIP [c0000000007eef3c] free_pud_range+0x8bc/0x8d0\n[ 2.553185] LR [c0000000007eef30] free_pud_range+0x8b0/0x8d0\n[ 2.553199] Call Trace:\n[ 2.553207] [c0000000622e7650] [c0000000007eef30] free_pud_range+0x8b0/0x8d0 (unreliable)\n[ 2.553229] [c0000000622e7750] [c0000000007f40b4] free_pgd_range+0x284/0x3b0\n[ 2.553248] [c0000000622e7800] [c0000000007f4630] free_pgtables+0x450/0x570\n[ 2.553274] [c0000000622e78e0] [c0000000008161c0] exit_mmap+0x250/0x650\n[ 2.553292] [c0000000622e7a30] [c0000000001b95b8] __mmput+0x98/0x290\n[ 2.558344] [c0000000622e7a80] [c0000000001d1018] exit_mm+0x118/0x1b0\n[ 2.558361] [c0000000622e7ac0] [c0000000001d141c] do_exit+0x2ec/0x870\n[ 2.558376] [c0000000622e7b60] [c0000000001d1ca8] do_group_exit+0x88/0x150\n[ 2.558391] [c0000000622e7bb0] [c0000000001d1db8] sys_exit_group+0x48/0x50\n[ 2.558407] [c0000000622e7be0] [c00000000003d810] system_call_exception+0x1e0/0x4c0\n[ 2.558423] [c0000000622e7e50] [c00000000000d05c] system_call_vectored_common+0x15c/0x2ec\n(...)\n[ 2.558892] ---[ end trace 0000000000000000 ]---\n[ 2.559022] BUG: Bad rss-counter state mm:000000002267cc9e type:MM_ANONPAGES val:1\n[ 2.559037] BUG: non-zero pgtables_bytes on freeing mm: -6144\n\nHere the modprobe process ended up with an allocated mm_struct from the\nmm_struct slab that was used before by the debug_vm_pgtable test. That is\nnot a problem, since the mm_stru\n---truncated---"
}
],
"lastModified": "2026-07-30T06:23:44.533",
"configurations": [
{
"nodes": [
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}