CVE-2026-74739
Estado: RecibidaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
net/sched: cls_u32: skip hash tables in u32_bind_class()
u32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode through the walker callback. u32_bind_class() unconditionally casts the passed fh to tc_u_knode and accesses &n->res, so when fh is actually a tc_u_hnode, which has no tcf_result member, this results in a slab-out-of-bounds read of res->classid in tc_cls_bind_class().
The issue can be reproduced with the following commands:
Fix this by skipping hash tables via the TC_U32_KEY(handle) check.
Detalles técnicos trazas, registros y código del informe original
tc qdisc add dev lo root handle 1: hfsc
tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit
tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1
tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbitCVSS
- 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: 0.18%
- Percentil entre todas las CVEs puntuadas: 6
- 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
T1005Data from Local Systemcollection75 %
Acceso local sin interacción (AV:L/PR:L/UI:N) que causa slab-out-of-bounds read: escalada de privilegios local mediante malconfiguración de qdisc. Lectura de memoria del kernel fuera de límites.
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)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/19d114b93c94bdef70496f26685c2a6b242f41b3
- https://git.kernel.org/stable/c/31f26a95eeee926946809ac456c61a3217936a62
- https://git.kernel.org/stable/c/594a064d603202b9ee21e07679d854e5c1750cc4
- https://git.kernel.org/stable/c/6d3724e616faf952c3adcf8414fc21a828ef3709
- https://git.kernel.org/stable/c/e71f8e9ed6f311410b14741f6012afe01869c0fa
- https://git.kernel.org/stable/c/ec5f3005586a785689fd568361b0c5925cb1548b
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-74739",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.8,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 1.8
}
]
},
"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": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1",
"lessThan": "ec5f3005586a785689fd568361b0c5925cb1548b",
"versionType": "git"
},
{
"status": "affected",
"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1",
"lessThan": "19d114b93c94bdef70496f26685c2a6b242f41b3",
"versionType": "git"
},
{
"status": "affected",
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"lessThan": "594a064d603202b9ee21e07679d854e5c1750cc4",
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},
{
"status": "affected",
"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1",
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"versionType": "git"
},
{
"status": "affected",
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"lessThan": "e71f8e9ed6f311410b14741f6012afe01869c0fa",
"versionType": "git"
},
{
"status": "affected",
"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1",
"lessThan": "6d3724e616faf952c3adcf8414fc21a828ef3709",
"versionType": "git"
}
],
"programFiles": [
"net/sched/cls_u32.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.184",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.153",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.105",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.46",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.10",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/sched/cls_u32.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-08-26T15:16:52.603",
"references": [
{
"url": "https://git.kernel.org/stable/c/19d114b93c94bdef70496f26685c2a6b242f41b3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/31f26a95eeee926946809ac456c61a3217936a62",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/594a064d603202b9ee21e07679d854e5c1750cc4",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/6d3724e616faf952c3adcf8414fc21a828ef3709",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e71f8e9ed6f311410b14741f6012afe01869c0fa",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/ec5f3005586a785689fd568361b0c5925cb1548b",
"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: cls_u32: skip hash tables in u32_bind_class()\n\nu32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode\nthrough the walker callback. u32_bind_class() unconditionally casts the\npassed fh to tc_u_knode and accesses &n->res, so when fh is actually a\ntc_u_hnode, which has no tcf_result member, this results in a\nslab-out-of-bounds read of res->classid in tc_cls_bind_class().\n\nThe issue can be reproduced with the following commands:\n\n tc qdisc add dev lo root handle 1: hfsc\n tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit\n tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1\n tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit\n\nFix this by skipping hash tables via the TC_U32_KEY(handle) check."
}
],
"lastModified": "2026-08-27T06:17:23.220",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}