CVE-2026-98011 (GCVE-0-2026-98011)
Vulnerability from cvelistv5
Published
2026-09-25 10:23
Modified
2026-10-19 09:12
Severity ?
Summary
In 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
References
Impacted products
Vendor Product Version
Linux Linux Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
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{
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          "programFiles": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "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"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:12:16.718Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a328698d046098e6f55b3b1460cac6bab577be58"
        },
        {
          "url": "https://git.kernel.org/stable/c/c364ad3ab3c8a6bce469a5cbf02881ab1324c5da"
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        {
          "url": "https://git.kernel.org/stable/c/2c6dd9fc86d446a03728c43f3b96d9ae29aa058f"
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          "url": "https://git.kernel.org/stable/c/6570f326a6a96bedf3d1d1dab6acc9f8c29104ec"
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          "url": "https://git.kernel.org/stable/c/1113b674307ffddd402524bd1fd9d7d5629b705b"
        },
        {
          "url": "https://git.kernel.org/stable/c/2e77947bbf6c166e76c038663832d0914418f761"
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        {
          "url": "https://git.kernel.org/stable/c/0898c6f9fa9ce2632ae88bd0f34a878ccc6335af"
        },
        {
          "url": "https://git.kernel.org/stable/c/eb56a495f59baf6cad5ed80e3ffb9078098b1346"
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      ],
      "title": "net/sched: hhf: clamp quantum in change and init paths",
      "x_generator": {
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98011",
    "datePublished": "2026-09-25T10:23:35.338Z",
    "dateReserved": "2026-09-25T10:19:56.069Z",
    "dateUpdated": "2026-10-19T09:12:16.718Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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