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  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74284.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_hfsc: Don't make class passive twice\n\nupdate_vf() is called from two places for the same class during a single\ndequeue when the class's child qdisc (e.g. codel/fq_codel) drops its last\npackets while dequeuing:\n\n1. The child calls qdisc_tree_reduce_backlog(), which, now that the child\n   is empty, invokes hfsc_qlen_notify() -\u003e update_vf(cl, 0, 0) and turns\n   the class passive (cl_nactive is decremented up the hierarchy).\n\n2. hfsc_dequeue() then calls update_vf(cl, qdisc_pkt_len(skb), cur_time)\n   to charge the dequeued bytes.\n\nOn the second call the class is already passive, but its child qdisc is\nstill empty, so update_vf() arms go_passive again:\n\n      if (cl-\u003eqdisc-\u003eq.qlen == 0 \u0026\u0026 cl-\u003ecl_flags \u0026 HFSC_FSC)\n              go_passive = 1;\n\nThe leaf is then skipped by the cl_nactive == 0 check inside the loop,\nwhich does not clear go_passive, so the stale go_passive propagates to the\nparent and decrements its cl_nactive a second time. A parent that still\nhas other active children is driven to cl_nactive == 0 and removed from\nthe vttree, even though those siblings are still backlogged. They are\nnever dequeued again and the qdisc stalls.\n\nFix this by only arming go_passive when the class is actually active, so an\nalready-passive class no longer triggers a second passive transition. The\nbyte accounting (cl-\u003ecl_total += len) still runs for every ancestor, so\ndequeued bytes continue to be counted exactly once.",
  "id": "CVE-2026-74284",
  "modified": "2026-08-18T03:31:08.366303822Z",
  "published": "2026-08-15T05:57:53.290Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/15720cd8fa3fc625146128f89a8e11b0449a20a7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3a49bbae676fef1ffe548971e6229ae2adeb9d10"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/66dbb13eeb2fc339f8f548a9076be4c1a94857b0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/90b662ea25f5e83bb3b8ccec5b93ced810b92fb8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9221a594c72a1446137926d4c2aa04e345f798dc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a425c82ff06cda5165e0de3de8c2a445ec1f863e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b2a017bfcf565721918ec7355a373911d2f2a227"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fc973ecd1a079b9a87c360478542f3a56dea085b"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74284.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74284"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "net/sched: sch_hfsc: Don't make class passive twice"
}