CVE-2026-90073
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: hhf: clamp quantum before hhf_change() to avoid overflow hhf_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) with no overflow check. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes weight * quantum overflow the signed deficit in hhf_dequeue(), spinning forever. Clamp q->quantum before hhf_change() so both the opt and !opt paths see a sane quantum. Without this, bare "tc qdisc add ... hhf" succeeds with a clamped quantum but "tc qdisc add ... hhf limit 1000" (any option present) fails with -EINVAL because hhf_change() re-validates the unclamped default (sch_hhf.c:559). 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 17:16:56.387000
Last modified
2026-10-19 09:18:56.040000
View original CVE JSON
{
"id": "CVE-2026-90073",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-17T17:16:56.387",
"lastModified": "2026-10-19T09:18:56.040",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: hhf: clamp quantum before hhf_change() to avoid overflow\n\nhhf_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) with no overflow\ncheck. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting\nMTU 2147483634) makes weight * quantum overflow the signed deficit in\nhhf_dequeue(), spinning forever.\n\nClamp q->quantum before hhf_change() so both the opt and !opt paths see\na sane quantum. Without this, bare \"tc qdisc add ... hhf\" succeeds with\na clamped quantum but \"tc qdisc add ... hhf limit 1000\" (any option\npresent) fails with -EINVAL because hhf_change() re-validates the\nunclamped default (sch_hhf.c:559). 256 matches fq_codel's floor and is\na 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": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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{
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"lessThanOrEqual": "5.15.*",
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{
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"lessThanOrEqual": "6.1.*",
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{
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{
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"metrics": {},
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