{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4"
            },
            {
              "fixed": "423a46053788ec4a021d57e69d66db7f7f550da4"
            },
            {
              "fixed": "95114e421196250e3d9662f12df442799477d3c3"
            },
            {
              "fixed": "e7183b7d518ce8b3e1f7284f9881d7a87569df14"
            },
            {
              "fixed": "181cb48c1e9af6b402567e132f879f89d1c54131"
            },
            {
              "fixed": "e7ea63b4195a150604993044ab574d8240f2a399"
            },
            {
              "fixed": "afae89de73dd693cfa329580ba0fba63bd3f0a11"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.191"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.160"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.113"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.57"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98968.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\namt: send the relay's General Query directly from the receive path\n\nAn skb queued in a qdisc can outlive the tunnel it references\nthrough a raw pointer in skb-\u003ecb. For example, with igmp_qrv set\nto 1 on the relay a tunnel lives for 135s, so a netem delay of\n180s on the amt device outlives it; when the tunnel expires and is\nfreed, the subsequent dequeue triggers a use-after-free in\namt_dev_xmit().\n\n  BUG: KASAN: slab-use-after-free in amt_dev_xmit+0x2763/0x2e20\n  Call Trace:\n   amt_dev_xmit+0x2763/0x2e20 [drivers/net/amt.c:1262]\n   dev_hard_start_xmit+0x22f/0x620\n   sch_direct_xmit+0x12e/0xac0\n   netem_dequeue+0x333/0xc50\n   net_tx_action+0x35c/0xa60\n\namt_send_igmp_gq() and amt_send_mld_gq() are only called from\namt_request_handler(), inside the rcu_read_lock_bh() section of\namt_rcv(). amt_request_handler() already has the tunnel the query is\nfor: it found or created it inside that section. Queuing the query with\ndev_queue_xmit() only leads back into amt_dev_xmit(), which strips the\nEthernet header and calls amt_send_membership_query() for that tunnel.\n\nMake that call directly from the two senders instead, the same way\namt_send_advertisement() transmits from the receive path. The query\nnever waits in a qdisc, the tunnel is only dereferenced inside the\nRCU section that found or created it, and nothing is stored in\nskb-\u003ecb, so no lookup or refcount is needed. Remove the query branch\nof amt_dev_xmit(), amt_skb_cb() and struct amt_skb_cb, which have no\nusers left.\n\nBehaviour changes:\n - The relay's own General Queries no longer pass through the amt\n   device's egress path: its qdisc, tc egress (clsact/tcx), the\n   netfilter egress hook and packet taps. They are still visible as\n   UDP on the underlay.\n - A query that is sent successfully is no longer counted as\n   tx_dropped. The old query branch left through the unlock label,\n   which counted every sent query as dropped.\n - A query that reaches amt_dev_xmit() on a relay from elsewhere,\n   such as a userspace querier, is now dropped at the IGMP/MLD type\n   switch. Before, it trusted whatever skb-\u003ecb held, and a NULL\n   tunnel hit the WARN_ON(1).",
  "id": "CVE-2026-98968",
  "modified": "2026-11-01T02:30:43.943159707Z",
  "published": "2026-10-23T12:19:39.236Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/181cb48c1e9af6b402567e132f879f89d1c54131"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/423a46053788ec4a021d57e69d66db7f7f550da4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/95114e421196250e3d9662f12df442799477d3c3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/afae89de73dd693cfa329580ba0fba63bd3f0a11"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e7183b7d518ce8b3e1f7284f9881d7a87569df14"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e7ea63b4195a150604993044ab574d8240f2a399"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98968.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98968"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "amt: send the relay's General Query directly from the receive path"
}