{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/amt.c",
            "include/net/amt.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "423a46053788ec4a021d57e69d66db7f7f550da4",
              "status": "affected",
              "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
              "versionType": "git"
            },
            {
              "lessThan": "95114e421196250e3d9662f12df442799477d3c3",
              "status": "affected",
              "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
              "versionType": "git"
            },
            {
              "lessThan": "e7183b7d518ce8b3e1f7284f9881d7a87569df14",
              "status": "affected",
              "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
              "versionType": "git"
            },
            {
              "lessThan": "181cb48c1e9af6b402567e132f879f89d1c54131",
              "status": "affected",
              "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
              "versionType": "git"
            },
            {
              "lessThan": "e7ea63b4195a150604993044ab574d8240f2a399",
              "status": "affected",
              "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
              "versionType": "git"
            },
            {
              "lessThan": "afae89de73dd693cfa329580ba0fba63bd3f0a11",
              "status": "affected",
              "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/amt.c",
            "include/net/amt.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.16"
            },
            {
              "lessThan": "5.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.113",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.57",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.191",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.113",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.57",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.11",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\namt: send the relay\u0027s 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\u0027s own General Queries no longer pass through the amt\n   device\u0027s 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)."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - A routable UDP AMT_MSG_REQUEST enters udp_rcv() and amt_rcv(), and amt_request_handler() uses its source tuple, nonce, and p bit in the patched amt_send_igmp_gq()/amt_send_mld_gq(); the resulting query later dequeues into patched amt_dev_xmit().\nAC:H - The remote attacker can send the Request and let the tunnel expire, but cannot arrange the required relay-local queue retention: the demonstrated trigger uses igmp_qrv=1 for a 135-second amt_gmi() and a 180-second netem delay. Success therefore depends on target state outside remote control.\nPR:N - The relay branch of amt_rcv() dispatches AMT_MSG_REQUEST directly to amt_request_handler(), which checks only length and reserved/version bits before creating a tunnel; it requires no Discovery state, nonce/MAC validation, credentials, or capability.\nUI:N - Once the relay and delaying qdisc exist, the attacker only sends a Request; amt_request_handler() schedules gc_wq, and amt_tunnel_expire() plus netem dequeue run without victim action.\nS:U - The freed amt_tunnel_list and the accesses from amt_dev_xmit()/amt_send_membership_query() remain within the relay host\u0027s kernel; no VM, IOMMU, or other authority boundary is crossed.\nC:H - amt_send_membership_query() reads freed tunnel-\u003eip4, source_port, nonce, and mac, and emits the nonce and MAC in an outbound AMT Membership Query; reclaiming the slab makes this a kernel UAF disclosure primitive.\nI:H - After transmission, amt_update_relay_status() executes spin_lock_bh(\u0026tunnel-\u003elock) and writes tunnel-\u003estatus through the freed or reallocated amt_tunnel_list, enabling kernel heap corruption and potential control-flow hijacking.\nA:H - The delayed dequeue in amt_dev_xmit() produced the reported KASAN slab-use-after-free; its stale routing, lock, and status accesses can oops, panic, or hang the kernel, and new Requests can trigger it again after tunnel expiry."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-30T12:40:34.695Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/423a46053788ec4a021d57e69d66db7f7f550da4"
        },
        {
          "url": "https://git.kernel.org/stable/c/95114e421196250e3d9662f12df442799477d3c3"
        },
        {
          "url": "https://git.kernel.org/stable/c/e7183b7d518ce8b3e1f7284f9881d7a87569df14"
        },
        {
          "url": "https://git.kernel.org/stable/c/181cb48c1e9af6b402567e132f879f89d1c54131"
        },
        {
          "url": "https://git.kernel.org/stable/c/e7ea63b4195a150604993044ab574d8240f2a399"
        },
        {
          "url": "https://git.kernel.org/stable/c/afae89de73dd693cfa329580ba0fba63bd3f0a11"
        }
      ],
      "title": "amt: send the relay\u0027s General Query directly from the receive path",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98968",
    "datePublished": "2026-10-23T12:19:39.236Z",
    "dateReserved": "2026-09-25T10:25:14.383Z",
    "dateUpdated": "2026-10-30T12:40:34.695Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}