CVE-2025-21855
Estado: ModificadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
ibmvnic: Don't reference skb after sending to VIOS
Previously, after successfully flushing the xmit buffer to VIOS, the tx_bytes stat was incremented by the length of the skb.
Detalles técnicos trazas, registros y código del informe original
It is invalid to access the skb memory after sending the buffer to the VIOS because, at any point after sending, the VIOS can trigger an interrupt to free this memory. A race between reading skb->len and freeing the skb is possible (especially during LPM) and will result in use-after-free: ================================================================== BUG: KASAN: slab-use-after-free in ibmvnic_xmit+0x75c/0x1808 [ibmvnic] Read of size 4 at addr c00000024eb48a70 by task hxecom/14495 <...> Call Trace: [c000000118f66cf0] [c0000000018cba6c] dump_stack_lvl+0x84/0xe8 (unreliable) [c000000118f66d20] [c0000000006f0080] print_report+0x1a8/0x7f0 [c000000118f66df0] [c0000000006f08f0] kasan_report+0x128/0x1f8 [c000000118f66f00] [c0000000006f2868] __asan_load4+0xac/0xe0 [c000000118f66f20] [c0080000046eac84] ibmvnic_xmit+0x75c/0x1808 [ibmvnic] [c000000118f67340] [c0000000014be168] dev_hard_start_xmit+0x150/0x358 <...> Freed by task 0: kasan_save_stack+0x34/0x68 kasan_save_track+0x2c/0x50 kasan_save_free_info+0x64/0x108 __kasan_mempool_poison_object+0x148/0x2d4 napi_skb_cache_put+0x5c/0x194 net_tx_action+0x154/0x5b8 handle_softirqs+0x20c/0x60c do_softirq_own_stack+0x6c/0x88 <...> The buggy address belongs to the object at c00000024eb48a00 which belongs to the cache skbuff_head_cache of size 224 ==================================================================
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: 0.44%
- Percentil entre todas las CVEs puntuadas: 36
- 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 Interpreterexecution70 %
Vulnerabilidad de use-after-free (CWE-416) en kernel Linux que requiere acceso local (AV:L) y privilegios de usuario (PR:L). Permite ejecución de código arbitrario con permisos elevados mediante corrupción de memoria del kernel.
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)
CWE
- CWE-416
- CWE-416
Referencias
- https://git.kernel.org/stable/c/093b0e5c90592773863f300b908b741622eef597
- https://git.kernel.org/stable/c/25dddd01dcc8ef3acff964dbb32eeb0d89f098e9
- https://git.kernel.org/stable/c/501ac6a7e21b82e05207c6b4449812d82820f306
- https://git.kernel.org/stable/c/abaff2717470e4b5b7c0c3a90e128b211a23da09
- https://git.kernel.org/stable/c/bdf5d13aa05ec314d4385b31ac974d6c7e0997c9
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nibmvnic: Don't reference skb after sending to VIOS\n\nPreviously, after successfully flushing the xmit buffer to VIOS,\nthe tx_bytes stat was incremented by the length of the skb.\n\nIt is invalid to access the skb memory after sending the buffer to\nthe VIOS because, at any point after sending, the VIOS can trigger\nan interrupt to free this memory. A race between reading skb->len\nand freeing the skb is possible (especially during LPM) and will\nresult in use-after-free:\n ==================================================================\n BUG: KASAN: slab-use-after-free in ibmvnic_xmit+0x75c/0x1808 [ibmvnic]\n Read of size 4 at addr c00000024eb48a70 by task hxecom/14495\n <...>\n Call Trace:\n [c000000118f66cf0] [c0000000018cba6c] dump_stack_lvl+0x84/0xe8 (unreliable)\n [c000000118f66d20] [c0000000006f0080] print_report+0x1a8/0x7f0\n [c000000118f66df0] [c0000000006f08f0] kasan_report+0x128/0x1f8\n [c000000118f66f00] [c0000000006f2868] __asan_load4+0xac/0xe0\n [c000000118f66f20] [c0080000046eac84] ibmvnic_xmit+0x75c/0x1808 [ibmvnic]\n [c000000118f67340] [c0000000014be168] dev_hard_start_xmit+0x150/0x358\n <...>\n Freed by task 0:\n kasan_save_stack+0x34/0x68\n kasan_save_track+0x2c/0x50\n kasan_save_free_info+0x64/0x108\n __kasan_mempool_poison_object+0x148/0x2d4\n napi_skb_cache_put+0x5c/0x194\n net_tx_action+0x154/0x5b8\n handle_softirqs+0x20c/0x60c\n do_softirq_own_stack+0x6c/0x88\n <...>\n The buggy address belongs to the object at c00000024eb48a00 which\n belongs to the cache skbuff_head_cache of size 224\n=================================================================="
},
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"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ibmvnic: No hacer referencia a skb después de enviar a VIOS. Anteriormente, tras vaciar correctamente el búfer de transmisión a VIOS, la estadística tx_bytes se incrementaba según la longitud de skb. No es posible acceder a la memoria de skb después de enviar el búfer a VIOS, ya que, en cualquier momento posterior al envío, VIOS puede activar una interrupción para liberar esta memoria. Es posible que se produzca una carrera entre la lectura de skb->len y la liberación de skb (especialmente durante LPM) y esto dará como resultado un uso después de la liberación: ======================================================================== ERROR KASAN: slab-use-after-free in ibmvnic_xmit+0x75c/0x1808 [ibmvnic] Read of size 4 at addr c00000024eb48a70 by task hxecom/14495 <...> Call Trace: [c000000118f66cf0] [c0000000018cba6c] dump_stack_lvl+0x84/0xe8 (unreliable) [c000000118f66d20] [c0000000006f0080] print_report+0x1a8/0x7f0 [c000000118f66df0] [c0000000006f08f0] kasan_report+0x128/0x1f8 [c000000118f66f00] [c0000000006f2868] __asan_load4+0xac/0xe0 [c000000118f66f20] [c0080000046eac84] ibmvnic_xmit+0x75c/0x1808 [ibmvnic] [c000000118f67340] [c0000000014be168] dev_hard_start_xmit+0x150/0x358 <...> Freed by task 0: kasan_save_stack+0x34/0x68 kasan_save_track+0x2c/0x50 kasan_save_free_info+0x64/0x108 __kasan_mempool_poison_object+0x148/0x2d4 napi_skb_cache_put+0x5c/0x194 net_tx_action+0x154/0x5b8 handle_softirqs+0x20c/0x60c do_softirq_own_stack+0x6c/0x88 <...> The buggy address belongs to the object at c00000024eb48a00 which belongs to the cache skbuff_head_cache of size 224 ======================================================================="
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"lastModified": "2026-07-30T06:21:41.357",
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