{
  "cveId": "CVE-2026-98968",
  "url": "https://patchblox.com/security/cve/CVE-2026-98968",
  "summary": "CVE-2026-98968 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-98968, released October 24, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "amt: send the relay\u0027s General Query directly from the receive path",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  amt: send the relay\u0027s General Query directly from the receive path  An skb queued in a qdisc can outlive the tunnel it references through a raw pointer in skb-\u003Ecb. For example, with igmp_qrv set to 1 on the relay a tunnel lives for 135s, so a netem delay of 180s on the amt device outlives it; when the tunnel expires and is freed, the subsequent dequeue triggers a use-after-free in amt_dev_xmit().    BUG: KASAN: slab-use-after-free in amt_dev_xmit\u002B0x2763/0x2e20   Call Trace:    amt_dev_xmit\u002B0x2763/0x2e20 [drivers/net/amt.c:1262]    dev_hard_start_xmit\u002B0x22f/0x620    sch_direct_xmit\u002B0x12e/0xac0    netem_dequeue\u002B0x333/0xc50    net_tx_action\u002B0x35c/0xa60  amt_send_igmp_gq() and amt_send_mld_gq() are only called from amt_request_handler(), inside the rcu_read_lock_bh() section of amt_rcv(). amt_request_handler() already has the tunnel the query is for: it found or created it inside that section. Queuing the query with dev_queue_xmit() only leads back into amt_dev_xmit(), which strips the Ethernet header and calls amt_send_membership_query() for that tunnel.  Make that call directly from the two senders instead, the same way amt_send_advertisement() transmits from the receive path. The query never waits in a qdisc, the tunnel is only dereferenced inside the RCU section that found or created it, and nothing is stored in skb-\u003Ecb, so no lookup or refcount is needed. Remove the query branch of amt_dev_xmit(), amt_skb_cb() and struct amt_skb_cb, which have no users left.  Behaviour changes:  - The relay\u0027s own General Queries no longer pass through the amt    device\u0027s egress path: its qdisc, tc egress (clsact/tcx), the    netfilter egress hook and packet taps. They are still visible as    UDP on the underlay.  - A query that is sent successfully is no longer counted as    tx_dropped. The old query branch left through the unlock label,    which counted every sent query as dropped.  - A query that reaches amt_dev_xmit() on a relay from elsewhere,    such as a userspace querier, is now dropped at the IGMP/MLD type    switch. Before, it trusted whatever skb-\u003Ecb held, and a NULL    tunnel hit the WARN_ON(1).",
  "published": "2026-10-23T13:17:18Z",
  "severity": "Important",
  "cvss": 8.1,
  "cvssVector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00532,
  "epssPercentile": 0.4518,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98968",
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.113-1",
      "fix": "DEBIAN-CVE-2026-98968",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-98968",
      "released": "2026-10-24T13:25:57Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.11-1",
      "fix": "DEBIAN-CVE-2026-98968",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-98968",
      "released": "2026-10-24T13:25:57Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T00:53:09Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}