CVE-2026-90074
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: fq_pie: clamp default quantum to avoid signed overflow fq_pie_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) without clamping. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes psched_mtu() return 0x80000000, which overflows the signed flow->deficit to INT_MIN in fq_pie_qdisc_dequeue(), causing an infinite loop and soft lockup. Emulate fq_pie_policy which is already bounded to [1, 1 << 20]; clamp the default to [256, 1 << 20]. 256 matches fq_codel's floor and is a sane minimum for a DRR quantum. Conditions to recreate the bug: a device whose MTU (plus hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy device with max_mtu == 0 accepting MTU 2147483634). Requires CAP_NET_ADMIN in a user namespace.
Severity
Not scored
CVSS score
Not available
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-09-17 17:16:56.530000
Last modified
2026-10-19 09:18:56.170000
View original CVE JSON
{
"id": "CVE-2026-90074",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-17T17:16:56.530",
"lastModified": "2026-10-19T09:18:56.170",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq_pie: clamp default quantum to avoid signed overflow\n\nfq_pie_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) without\nclamping. A device with a huge MTU (e.g. dummy with max_mtu == 0\naccepting MTU 2147483634) makes psched_mtu() return 0x80000000, which\noverflows the signed flow->deficit to INT_MIN in fq_pie_qdisc_dequeue(),\ncausing an infinite loop and soft lockup. Emulate fq_pie_policy which\nis already bounded to [1, 1 << 20]; clamp the default to [256, 1 << 20].\n256 matches fq_codel's floor and is a sane minimum for a DRR quantum.\n\nConditions to recreate the bug: a device whose MTU (plus\nhard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy\ndevice with max_mtu == 0 accepting MTU 2147483634). Requires\nCAP_NET_ADMIN in a user namespace."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/sched/sch_fq_pie.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
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},
{
"version": "5.10.270",
"lessThanOrEqual": "5.10.*",
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"status": "unaffected"
},
{
"version": "5.15.221",
"lessThanOrEqual": "5.15.*",
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},
{
"version": "6.1.188",
"lessThanOrEqual": "6.1.*",
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"status": "unaffected"
},
{
"version": "6.6.157",
"lessThanOrEqual": "6.6.*",
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"status": "unaffected"
},
{
"version": "6.12.110",
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},
{
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}
]
}
]
}
],
"metrics": {},
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