CVE-2026-90076
In the Linux kernel, the following vulnerability has been resolved:
net/sched: fq: add overflow bounds to quantum and initial quantum
fq_init() computes quantum = 2 * psched_mtu() and initial_quantum = 10 * psched_mtu() with no overflow check. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes psched_mtu() return 0x80000000; the 2 * and 10 * multiplications wrap to 0 in 32-bit arithmetic, so q->quantum == 0. Then in fq_dequeue() the credit-refill loop adds 0 to f->credit (which stays <= 0) and goto begin loops forever under the qdisc lock, creating a soft lockup.
Leer descripción completaMostrar menos
Clamp psched_mtu() to [1, 1 << 20] before multiplying so the product cannot wrap, then cap the result at 1 << 20, matching the bound already enforced on TCA_FQ_QUANTUM in fq_change().
Conditions to recreate the bug: a device whose MTU (plus hard_header_len) is large enough that 2 * psched_mtu() wraps (e.g. a dummy device with max_mtu == 0 accepting MTU 2147483634). Requires CAP_NET_ADMIN in a user namespace.
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- 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)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-90076",
"cveTags": [],
"metrics": {},
"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": "afe4fd062416b158a8a8538b23adc1930a9b88dc",
"lessThan": "d16dac3925be95ad46e986d4b139c9898b6e227f",
"versionType": "git"
},
{
"status": "affected",
"version": "afe4fd062416b158a8a8538b23adc1930a9b88dc",
"lessThan": "f6b3e3848a5fca63438984acd6d9eceac80814c1",
"versionType": "git"
},
{
"status": "affected",
"version": "afe4fd062416b158a8a8538b23adc1930a9b88dc",
"lessThan": "e35acd56f244d94355f9ab237c2ecc8fba5e6f04",
"versionType": "git"
},
{
"status": "affected",
"version": "afe4fd062416b158a8a8538b23adc1930a9b88dc",
"lessThan": "709f34f7c28dc4dd6c40343d101850f11e172312",
"versionType": "git"
}
],
"programFiles": [
"net/sched/sch_fq.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.12"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.12",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.110",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.52",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/sched/sch_fq.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-17T17:16:56.820",
"references": [
{
"url": "https://git.kernel.org/stable/c/709f34f7c28dc4dd6c40343d101850f11e172312",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d16dac3925be95ad46e986d4b139c9898b6e227f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e35acd56f244d94355f9ab237c2ecc8fba5e6f04",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f6b3e3848a5fca63438984acd6d9eceac80814c1",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq: add overflow bounds to quantum and initial quantum\n\nfq_init() computes quantum = 2 * psched_mtu() and initial_quantum = 10 *\npsched_mtu() with no overflow check. A device with a huge MTU (e.g. dummy\nwith max_mtu == 0 accepting MTU 2147483634) makes psched_mtu() return\n0x80000000; the 2 * and 10 * multiplications wrap to 0 in 32-bit\narithmetic, so q->quantum == 0. Then in fq_dequeue() the credit-refill\nloop adds 0 to f->credit (which stays <= 0) and goto begin loops\nforever under the qdisc lock, creating a soft lockup.\n\nClamp psched_mtu() to [1, 1 << 20] before multiplying so the product\ncannot wrap, then cap the result at 1 << 20, matching the bound already\nenforced on TCA_FQ_QUANTUM in fq_change().\n\nConditions to recreate the bug: a device whose MTU (plus\nhard_header_len) is large enough that 2 * psched_mtu() wraps (e.g. a\ndummy device with max_mtu == 0 accepting MTU 2147483634). Requires\nCAP_NET_ADMIN in a user namespace."
}
],
"lastModified": "2026-09-17T17:16:56.820",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}