CVE-2026-98012 (GCVE-0-2026-98012)
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: 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
References
Impacted products
Vendor Product Version
Linux Linux Version: 4919649699c5f4dbae08b8e2ed536fc9d6c3c2aa
Version: 548cf048b426729a7a1fa6acd1271c010c9a7380
Version: c49ac48fac51a6a54efd5963954d02bacf075085
Version: 58ae7465f0e7113d45aa88a66bf2d203c71c195e
Version: 82bd38bd5467ece1ee274b493f51326cf5220a5a
Version: e4650d7ae4252f67e997a632adfae0dd74d3a99a
Version: e4650d7ae4252f67e997a632adfae0dd74d3a99a
Version: e4650d7ae4252f67e997a632adfae0dd74d3a99a
Version: 843cacb88f42f426973f1ed11c6fb562558efb27
Version: 5.10.239   ≤
Version: 5.15.186   ≤
Version: 6.1.129   ≤
Version: 6.6.76   ≤
Version: 6.12.13   ≤
Version: 5.4.297   ≤
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      "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-\u003equantum \u003c 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 \u003e 1\u003c\u003c20\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"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:12:17.681Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/4117c528b2de5fdc3e4a7e3626815b616a635cdc"
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        {
          "url": "https://git.kernel.org/stable/c/f82fa6f10d4a69322cad0f7a4aa523ce6292a5a0"
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        {
          "url": "https://git.kernel.org/stable/c/0692ce5a528df450d64e9f819054177e9d91076f"
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        {
          "url": "https://git.kernel.org/stable/c/e4192bcf83aaab02129644ddf4656fd86e93751f"
        },
        {
          "url": "https://git.kernel.org/stable/c/f3820dce042a673fcb28cc31c87ee14257e21a17"
        },
        {
          "url": "https://git.kernel.org/stable/c/534cd7ecbbc6e8a974f4003a5c1557439c6e0a72"
        },
        {
          "url": "https://git.kernel.org/stable/c/e6c1cb728e389354203a72bc77464c222a247aeb"
        },
        {
          "url": "https://git.kernel.org/stable/c/fb9f88a33c516ea5c0bcd9a22ca288b246b34567"
        }
      ],
      "title": "net/sched: sfq: clamp quantum in change path",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98012",
    "datePublished": "2026-09-25T10:23:35.934Z",
    "dateReserved": "2026-09-25T10:19:56.069Z",
    "dateUpdated": "2026-10-19T09:12:17.681Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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