CVE-2026-43496
Estado: AnalizadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked
When red qdisc has children (eg qfq qdisc) whose peek() callback is qdisc_peek_dequeued(), we could get a kernel panic. When the parent of such qdiscs (eg illustrated in patch #3 as tbf) wants to retrieve an skb from its child (red in this case), it will do the following: 1a. do a peek() - and when sensing there's an skb the child can offer, then - the child in this case(red) calls its child's (qfq) peek. qfq does the right thing and will return the gso_skb queue packet. Note: if there wasnt a gso_skb entry then qfq will store it there. 1b. invoke a dequeue() on the child (red). And herein lies the problem. - red will call the child's dequeue() which will essentially just try to grab something of qfq's queue.
Leer descripción completaMostrar menos
The right thing to do in #1b is to grab the skb off gso_skb queue. This patchset fixes that issue by changing #1b to use qdisc_dequeue_peeked() method instead.
Detalles técnicos trazas, registros y código del informe original
[ 78.667668][ T363] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f] [ 78.667927][ T363] CPU: 1 UID: 0 PID: 363 Comm: ping Not tainted 7.1.0-rc1-00033-g46f74a3f7d57-dirty #790 PREEMPT(full) [ 78.668263][ T363] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 78.668486][ T363] RIP: 0010:qfq_dequeue+0x446/0xc90 [sch_qfq] [ 78.668718][ T363] Code: 54 c0 e8 dd 90 00 f1 48 c7 c7 e0 03 54 c0 48 89 de e8 ce 90 00 f1 48 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <80> 3c 02 00 74 05 e8 ef a1 e1 f1 48 8b 7b 48 48 8d 54 24 58 48 8d [ 78.669312][ T363] RSP: 0018:ffff88810de573e0 EFLAGS: 00010216 [ 78.669533][ T363] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 78.669790][ T363] RDX: 0000000000000009 RSI: 0000000000000004 RDI: 0000000000000048 [ 78.670044][ T363] RBP: ffff888110dc4000 R08: ffffffffb1b0885a R09: fffffbfff6ba9078 [ 78.670297][ T363] R10: 0000000000000003 R11: ffff888110e31c80 R12: 0000001880000000 [ 78.670560][ T363] R13: ffff888110dc4150 R14: ffff888110dc42b8 R15: 0000000000000200 [ 78.670814][ T363] FS: 00007f66a8f09c40(0000) GS:ffff888163428000(0000) knlGS:0000000000000000 [ 78.671110][ T363] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 78.671324][ T363] CR2: 000055db4c6a30a8 CR3: 000000010da67000 CR4: 0000000000750ef0 [ 78.671585][ T363] PKRU: 55555554 [ 78.671713][ T363] Call Trace: [ 78.671843][ T363] <TASK> [ 78.671936][ T363] ? __pfx_qfq_dequeue+0x10/0x10 [sch_qfq] [ 78.672148][ T363] ? __pfx__printk+0x10/0x10 [ 78.672322][ T363] ? srso_alias_return_thunk+0x5/0xfbef5 [ 78.672496][ T363] ? lockdep_hardirqs_on_prepare+0xa8/0x1a0 [ 78.672706][ T363] ? srso_alias_return_thunk+0x5/0xfbef5 [ 78.672875][ T363] ? trace_hardirqs_on+0x19/0x1a0 [ 78.673047][ T363] red_dequeue+0x65/0x270 [sch_red] [ 78.673217][ T363] ? srso_alias_return_thunk+0x5/0xfbef5 [ 78.673385][ T363] tbf_dequeue.cold+0xb0/0x70c [sch_tbf] [ 78.673566][ T363] __qdisc_run+0x169/0x1900
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: 0.16%
- Percentil entre todas las CVEs puntuadas: 5
- 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
- CWE-476
Referencias
- https://git.kernel.org/stable/c/03b0aaeba082ae981a0dfe96cdd03d02050537a1
- https://git.kernel.org/stable/c/36aa34f42cb6842cf371f3a2d3e855d24fd57a50
- https://git.kernel.org/stable/c/458d5615272d3de535748342eb68ca492343048c
- https://git.kernel.org/stable/c/45cd83c5c470ba49fe261489c8358ad7b9df7c45
- https://git.kernel.org/stable/c/587dcf970a525f543d8b5855d9f37a4ca97b76ef
- https://git.kernel.org/stable/c/8d09618840b99ef00154d3e731ce9b11e096196d
- https://git.kernel.org/stable/c/c7335f4dc0fa21f7015b910c6fc2f4d599732328
- https://git.kernel.org/stable/c/ce051eede433f876d322ac3550a36a3c6fc4c231
JSON original (NVD)
Mostrar
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"cveTags": [],
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"source": "nvd@nist.gov",
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"baseScore": 5.5,
"attackVector": "LOCAL",
"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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"source": "nvd@nist.gov",
"description": [
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"lang": "en",
"value": "CWE-476"
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked\n\nWhen red qdisc has children (eg qfq qdisc) whose peek() callback is\nqdisc_peek_dequeued(), we could get a kernel panic. When the parent of such\nqdiscs (eg illustrated in patch #3 as tbf) wants to retrieve an skb from\nits child (red in this case), it will do the following:\n 1a. do a peek() - and when sensing there's an skb the child can offer, then\n - the child in this case(red) calls its child's (qfq) peek.\n qfq does the right thing and will return the gso_skb queue packet.\n Note: if there wasnt a gso_skb entry then qfq will store it there.\n 1b. invoke a dequeue() on the child (red). And herein lies the problem.\n - red will call the child's dequeue() which will essentially just\n try to grab something of qfq's queue.\n\n[ 78.667668][ T363] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]\n[ 78.667927][ T363] CPU: 1 UID: 0 PID: 363 Comm: ping Not tainted 7.1.0-rc1-00033-g46f74a3f7d57-dirty #790 PREEMPT(full)\n[ 78.668263][ T363] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[ 78.668486][ T363] RIP: 0010:qfq_dequeue+0x446/0xc90 [sch_qfq]\n[ 78.668718][ T363] Code: 54 c0 e8 dd 90 00 f1 48 c7 c7 e0 03 54 c0 48 89 de e8 ce 90 00 f1 48 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <80> 3c 02 00 74 05 e8 ef a1 e1 f1 48 8b 7b 48 48 8d 54 24 58 48 8d\n[ 78.669312][ T363] RSP: 0018:ffff88810de573e0 EFLAGS: 00010216\n[ 78.669533][ T363] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000\n[ 78.669790][ T363] RDX: 0000000000000009 RSI: 0000000000000004 RDI: 0000000000000048\n[ 78.670044][ T363] RBP: ffff888110dc4000 R08: ffffffffb1b0885a R09: fffffbfff6ba9078\n[ 78.670297][ T363] R10: 0000000000000003 R11: ffff888110e31c80 R12: 0000001880000000\n[ 78.670560][ T363] R13: ffff888110dc4150 R14: ffff888110dc42b8 R15: 0000000000000200\n[ 78.670814][ T363] FS: 00007f66a8f09c40(0000) GS:ffff888163428000(0000) knlGS:0000000000000000\n[ 78.671110][ T363] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 78.671324][ T363] CR2: 000055db4c6a30a8 CR3: 000000010da67000 CR4: 0000000000750ef0\n[ 78.671585][ T363] PKRU: 55555554\n[ 78.671713][ T363] Call Trace:\n[ 78.671843][ T363] <TASK>\n[ 78.671936][ T363] ? __pfx_qfq_dequeue+0x10/0x10 [sch_qfq]\n[ 78.672148][ T363] ? __pfx__printk+0x10/0x10\n[ 78.672322][ T363] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 78.672496][ T363] ? lockdep_hardirqs_on_prepare+0xa8/0x1a0\n[ 78.672706][ T363] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 78.672875][ T363] ? trace_hardirqs_on+0x19/0x1a0\n[ 78.673047][ T363] red_dequeue+0x65/0x270 [sch_red]\n[ 78.673217][ T363] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 78.673385][ T363] tbf_dequeue.cold+0xb0/0x70c [sch_tbf]\n[ 78.673566][ T363] __qdisc_run+0x169/0x1900\n\nThe right thing to do in #1b is to grab the skb off gso_skb queue.\nThis patchset fixes that issue by changing #1b to use qdisc_dequeue_peeked()\nmethod instead."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet/sched: sch_red: Reemplazar la llamada directa a dequeue con peek y qdisc_dequeue_peeked\n\nCuando red qdisc tiene hijos (por ejemplo, qfq qdisc) cuya función de devolución de llamada peek() es qdisc_peek_dequeued(), podríamos obtener un pánico del kernel. Cuando el padre de tales qdiscs (por ejemplo, ilustrado en el parche #3 como tbf) quiere recuperar un skb de su hijo (red en este caso), hará lo siguiente:\n 1a. hacer un peek() - y al detectar que hay un skb que el hijo puede ofrecer, entonces\n - el hijo en este caso (red) llama al peek de su hijo (qfq).\n qfq hace lo correcto y devolverá el paquete de la cola gso_skb.\n Nota: si no hubiera una entrada gso_skb, entonces qfq lo almacenará allí.\n 1b. invocar un dequeue() en el hijo (red). Y aquí radica el problema.\n - red llamará al dequeue() del hijo, que esencialmente solo intentará tomar algo de la cola de qfq.\n\n[ 78.667668][ T363] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]\n[ 78.667927][ T363] CPU: 1 UID: 0 PID: 363 Comm: ping Not tainted 7.1.0-rc1-00033-g46f74a3f7d57-dirty #790 PREEMPT(full)\n[ 78.668263][ T363] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[ 78.668486][ T363] RIP: 0010:qfq_dequeue+0x446/0xc90 [sch_qfq]\n[ 78.668718][ T363] Code: 54 c0 e8 dd 90 00 f1 48 c7 c7 e0 03 54 c0 48 89 de e8 ce 90 00 f1 48 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <80> 3c 02 00 74 05 e8 ef a1 e1 f1 48 8b 7b 48 48 8d 54 24 58 48 8d\n[ 78.669312][ T363] RSP: 0018:ffff88810de573e0 EFLAGS: 00010216\n[ 78.669533][ T363] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000\n[ 78.669790][ T363] RDX: 0000000000000009 RSI: 0000000000000004 RDI: 0000000000000048\n[ 78.670044][ T363] RBP: ffff888110dc4000 R08: ffffffffb1b0885a R09: fffffbfff6ba9078\n[ 78.670297][ T363] R10: 0000000000000003 R11: ffff888110e31c80 R12: 0000001880000000\n[ 78.670560][ T363] R13: ffff888110dc4150 R14: ffff888110dc42b8 R15: 0000000000000200\n[ 78.670814][ T363] FS: 00007f66a8f09c40(0000) GS:ffff888163428000(0000) knlGS:0000000000000000\n[ 78.671110][ T363] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 78.671324][ T363] CR2: 000055db4c6a30a8 CR3: 000000010da67000 CR4: 0000000000750ef0\n[ 78.671585][ T363] PKRU: 55555554\n[ 78.671713][ T363] Call Trace:\n[ 78.671843][ T363] <TASK>\n[ 78.671936][ T363] ? __pfx_qfq_dequeue+0x10/0x10 [sch_qfq]\n[ 78.672148][ T363] ? __pfx__printk+0x10/0x10\n[ 78.672322][ T363] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 78.672496][ T363] ? lockdep_hardirqs_on_prepare+0xa8/0x1a0\n[ 78.672706][ T363] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 78.672875][ T363] ? trace_hardirqs_on+0x19/0x1a0\n[ 78.673047][ T363] red_dequeue+0x65/0x270 [sch_red]\n[ 78.673217][ T363] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 78.673385][ T363] tbf_dequeue.cold+0xb0/0x70c [sch_tbf]\n[ 78.673566][ T363] __qdisc_run+0x169/0x1900\n\nLo correcto a hacer en #1b es tomar el skb de la cola gso_skb.\nEste conjunto de parches soluciona ese problema cambiando #1b para usar el método qdisc_dequeue_peeked() en su lugar."
}
],
"lastModified": "2026-07-23T16:10:00.137",
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