GHSA-93PC-W6VH-HG9R
Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 12:31In the Linux kernel, the following vulnerability has been resolved:
net/sched: hhf: clamp quantum in change and init paths
hhf_change() accepts any quantum from userspace, including 1. 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, ...) in hhf_change() matching fq_codel_change(). Clamp hhf_init() to [256, 1<<20] matching the siblings, and remove the old fallback that only set quantum=256 on overflow.
Conditions to recreate the bug: CONFIG_NET_SCH_HHF=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices).
tc qdisc add dev dummy0 root hhf tc qdisc change dev dummy0 root hhf quantum 1 stab data 32768 size_log 15 cell_log 0
{
"affected": [],
"aliases": [
"CVE-2026-98011"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-25T11:17:29Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: hhf: clamp quantum in change and init paths\n\nhhf_change() accepts any quantum from userspace, including 1. With a\ncrafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 makes\nthe deficit-refill loop spin ~2^31 times under the qdisc lock\n(a soft lockup / denial of service).\n\nAdd max(256U, ...) in hhf_change() matching fq_codel_change(). Clamp\nhhf_init() to [256, 1\u003c\u003c20] matching the siblings, and remove the old\nfallback that only set quantum=256 on overflow.\n\nConditions to recreate the bug:\n CONFIG_NET_SCH_HHF=y. Requires CAP_NET_ADMIN (namespace-local via\n unshare -Urn suffices).\n\n tc qdisc add dev dummy0 root hhf\n tc qdisc change dev dummy0 root hhf quantum 1 stab data 32768 size_log 15 cell_log 0",
"id": "GHSA-93pc-w6vh-hg9r",
"modified": "2026-09-25T12:31:32Z",
"published": "2026-09-25T12:31:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98011"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0898c6f9fa9ce2632ae88bd0f34a878ccc6335af"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1113b674307ffddd402524bd1fd9d7d5629b705b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2e77947bbf6c166e76c038663832d0914418f761"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/eb56a495f59baf6cad5ed80e3ffb9078098b1346"
}
],
"schema_version": "1.4.0",
"severity": []
}
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