CVE-2025-21925
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
llc: do not use skb_get() before dev_queue_xmit()
syzbot is able to crash hosts [1], using llc and devices not supporting IFF_TX_SKB_SHARING.
In this case, e1000 driver calls eth_skb_pad(), while the skb is shared.
Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c
Note that e1000 driver might have an issue with pktgen, because it does not clear IFF_TX_SKB_SHARING, this is an orthogonal change.
We need to audit other skb_get() uses in net/llc.
[1]
Detalles técnicos trazas, registros y código del informe original
kernel BUG at net/core/skbuff.c:2178 ! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178 Call Trace: <TASK> __skb_pad+0x18a/0x610 net/core/skbuff.c:2466 __skb_put_padto include/linux/skbuff.h:3843 [inline] skb_put_padto include/linux/skbuff.h:3862 [inline] eth_skb_pad include/linux/etherdevice.h:656 [inline] e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128 __netdev_start_xmit include/linux/netdevice.h:5151 [inline] netdev_start_xmit include/linux/netdevice.h:5160 [inline] xmit_one net/core/dev.c:3806 [inline] dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822 sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343 __dev_xmit_skb net/core/dev.c:4045 [inline] __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621 dev_queue_xmit include/linux/netdevice.h:3313 [inline] llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144 llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline] llc_sap_next_state net/llc/llc_sap.c:182 [inline] llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209 llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993 sock_sendmsg_nosec net/socket.c:718 [inline]
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.22%
- Percentil entre todas las CVEs puntuadas: 12
- 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).
Tecnologías afectadas (1)
CWE
- NVD-CWE-noinfo
Referencias
- https://git.kernel.org/stable/c/056e8a46d79e22983bae4267e0d9c52927076f46
- https://git.kernel.org/stable/c/0f764208dc24ea043c3e20194d32aebf94f8459c
- https://git.kernel.org/stable/c/13f3f872627f0f27c31245524fc11367756240ad
- https://git.kernel.org/stable/c/17f86e25431ebc15aa9245ff156414fdad47822d
- https://git.kernel.org/stable/c/416e8b4c20c6398044e93008deefd563289f477d
- https://git.kernel.org/stable/c/64e6a754d33d31aa844b3ee66fb93ac84ca1565e
- https://git.kernel.org/stable/c/9b6f083db141ece0024be01526aa05aa978811cb
- https://git.kernel.org/stable/c/cd1c44327bbbd50fc24f2b38892f5f328b784d0f
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
JSON original (NVD)
Mostrar
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"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "NONE"
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"descriptions": [
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nllc: do not use skb_get() before dev_queue_xmit()\n\nsyzbot is able to crash hosts [1], using llc and devices\nnot supporting IFF_TX_SKB_SHARING.\n\nIn this case, e1000 driver calls eth_skb_pad(), while\nthe skb is shared.\n\nSimply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c\n\nNote that e1000 driver might have an issue with pktgen,\nbecause it does not clear IFF_TX_SKB_SHARING, this is an\northogonal change.\n\nWe need to audit other skb_get() uses in net/llc.\n\n[1]\n\nkernel BUG at net/core/skbuff.c:2178 !\nOops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI\nCPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014\n RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178\nCall Trace:\n <TASK>\n __skb_pad+0x18a/0x610 net/core/skbuff.c:2466\n __skb_put_padto include/linux/skbuff.h:3843 [inline]\n skb_put_padto include/linux/skbuff.h:3862 [inline]\n eth_skb_pad include/linux/etherdevice.h:656 [inline]\n e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128\n __netdev_start_xmit include/linux/netdevice.h:5151 [inline]\n netdev_start_xmit include/linux/netdevice.h:5160 [inline]\n xmit_one net/core/dev.c:3806 [inline]\n dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822\n sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343\n __dev_xmit_skb net/core/dev.c:4045 [inline]\n __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621\n dev_queue_xmit include/linux/netdevice.h:3313 [inline]\n llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144\n llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline]\n llc_sap_next_state net/llc/llc_sap.c:182 [inline]\n llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209\n llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993\n sock_sendmsg_nosec net/socket.c:718 [inline]"
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: llc: no usar skb_get() antes de dev_queue_xmit(). syzbot puede bloquear hosts [1], usando llc y dispositivos que no admiten IFF_TX_SKB_SHARING. En este caso, el controlador e1000 llama a eth_skb_pad() mientras el skb está compartido. Simplemente reemplace skb_get() por skb_clone() en net/llc/llc_s_ac.c. Tenga en cuenta que el controlador e1000 podría tener un problema con pktgen, ya que no borra IFF_TX_SKB_SHARING; este es un cambio ortogonal. Necesitamos auditar otros usos de skb_get() en net/llc. [1] ¡ERROR del kernel en net/core/skbuff.c:2178! Oops: código de operación no válido: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 No contaminado 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0 Nombre del hardware: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 01/04/2014 RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178 Rastreo de llamadas: __skb_pad+0x18a/0x610 net/core/skbuff.c:2466 __skb_put_padto include/linux/skbuff.h:3843 [en línea] skb_put_padto include/linux/skbuff.h:3862 [en línea] eth_skb_pad include/linux/etherdevice.h:656 [en línea] e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128 __netdev_start_xmit include/linux/netdevice.h:5151 [en línea] netdev_start_xmit include/linux/netdevice.h:5160 [en línea] xmit_one net/core/dev.c:3806 [en línea] dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822 sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343 __dev_xmit_skb net/core/dev.c:4045 [en línea] __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621 dev_queue_xmit include/linux/netdevice.h:3313 [en línea] llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144 llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [en línea] llc_sap_next_state net/llc/llc_sap.c:182 [en línea] llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209 llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993 sock_sendmsg_nosec net/socket.c:718 [en línea]"
}
],
"lastModified": "2026-07-14T13:17:27.100",
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