CVE-2026-98012
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: sfq: clamp quantum in change path sfq_change() accepts any non-negative quantum (only rejects (int)ctl->quantum < 0). With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 makes the deficit-refill loop spin ~2^31 times under the qdisc lock (a soft lockup / denial of service). Add max(256U, ...) matching fq_codel_change(). Reject quantum > 1<<20 with -EINVAL, matching fq_codel_change() and the init clamp. Conditions to recreate the bug: CONFIG_NET_SCH_SFQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root sfq tc qdisc change dev dummy0 root sfq quantum 1 stab data 32768 size_log 15 cell_log 0
Severity
Not scored
CVSS score
Not available
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-09-25 11:17:29.537000
Last modified
2026-10-19 10:17:54.200000
View original CVE JSON
{
"id": "CVE-2026-98012",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-25T11:17:29.537",
"lastModified": "2026-10-19T10:17:54.200",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sfq: clamp quantum in change path\n\nsfq_change() accepts any non-negative quantum (only rejects\n(int)ctl->quantum < 0). With a crafted size table qdisc_pkt_len reaches\n~2 GiB, so quantum=1 makes the deficit-refill loop spin ~2^31 times\nunder the qdisc lock (a soft lockup / denial of service).\n\nAdd max(256U, ...) matching fq_codel_change(). Reject quantum > 1<<20\nwith -EINVAL, matching fq_codel_change() and the init clamp.\n\nConditions to recreate the bug:\n CONFIG_NET_SCH_SFQ=y. Requires CAP_NET_ADMIN (namespace-local via\n unshare -Urn suffices).\n\n tc qdisc add dev dummy0 root sfq\n tc qdisc change dev dummy0 root sfq quantum 1 stab data 32768 size_log 15 cell_log 0"
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/sched/sch_sfq.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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{
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"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"net/sched/sch_sfq.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"versionType": "original_commit_for_fix",
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}
]
}
]
}
],
"metrics": {},
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