{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "d16dac3925be95ad46e986d4b139c9898b6e227f"
            },
            {
              "fixed": "a27498d34c3f429fb6db3aa609569f8154afa175"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "f6b3e3848a5fca63438984acd6d9eceac80814c1"
            },
            {
              "fixed": "798283cd0fe7ba997f67e5a917f14ab40afa8d9f"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "e35acd56f244d94355f9ab237c2ecc8fba5e6f04"
            },
            {
              "fixed": "72e9387884554f47b03bfd40fb8b2bf52789c68d"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "709f34f7c28dc4dd6c40343d101850f11e172312"
            },
            {
              "fixed": "094cc07f98dfe70a34e2a1923af17fd29b8cf622"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90050.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq: clamp quantum and initial_quantum in change path\n\nThe fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and\nTCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to\n[1, 1\u003c\u003c20]. A user can override the init clamp via tc qdisc change,\nrestoring the small-quantum deficit spin that the init clamp prevents.\n\nNarrow iq_range.max to 1\u003c\u003c20 so TCA_FQ_INITIAL_QUANTUM is rejected at\nparse time. Clamp TCA_FQ_QUANTUM to [256, 1\u003c\u003c20] in fq_change() and\nfq_init() quantum to [256, 1\u003c\u003c20] for tiny-MTU devices.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root fq\n  tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0",
  "id": "CVE-2026-90050",
  "modified": "2026-09-19T03:31:04.885231050Z",
  "published": "2026-09-17T16:05:36.970Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/094cc07f98dfe70a34e2a1923af17fd29b8cf622"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/72e9387884554f47b03bfd40fb8b2bf52789c68d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/798283cd0fe7ba997f67e5a917f14ab40afa8d9f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a27498d34c3f429fb6db3aa609569f8154afa175"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90050.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90050"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "net/sched: fq: clamp quantum and initial_quantum in change path"
}