{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.180-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.100-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.1.5-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  net/sched: sch_hfsc: Don't make class passive twice  update_vf() is called from two places for the same class during a single dequeue when the class's child qdisc (e.g. codel/fq_codel) drops its last packets while dequeuing:  1. The child calls qdisc_tree_reduce_backlog(), which, now that the child    is empty, invokes hfsc_qlen_notify() -\u003e update_vf(cl, 0, 0) and turns    the class passive (cl_nactive is decremented up the hierarchy).  2. hfsc_dequeue() then calls update_vf(cl, qdisc_pkt_len(skb), cur_time)    to charge the dequeued bytes.  On the second call the class is already passive, but its child qdisc is still empty, so update_vf() arms go_passive again:        if (cl-\u003eqdisc-\u003eq.qlen == 0 \u0026\u0026 cl-\u003ecl_flags \u0026 HFSC_FSC)               go_passive = 1;  The leaf is then skipped by the cl_nactive == 0 check inside the loop, which does not clear go_passive, so the stale go_passive propagates to the parent and decrements its cl_nactive a second time. A parent that still has other active children is driven to cl_nactive == 0 and removed from the vttree, even though those siblings are still backlogged. They are never dequeued again and the qdisc stalls.  Fix this by only arming go_passive when the class is actually active, so an already-passive class no longer triggers a second passive transition. The byte accounting (cl-\u003ecl_total += len) still runs for every ancestor, so dequeued bytes continue to be counted exactly once.",
  "id": "DEBIAN-CVE-2026-74284",
  "modified": "2026-09-14T16:47:33.822617236Z",
  "published": "2026-08-15T06:22:27.903Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-74284"
    }
  ],
  "upstream": [
    "CVE-2026-74284"
  ]
}