{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76"
            },
            {
              "fixed": "b712da45bd9b9835d132e9fbc0c3e43c164cb1fd"
            },
            {
              "fixed": "f82a2ded3d7a9098267c84f14eafdb98c4550ac5"
            },
            {
              "fixed": "b322532a4b774db1b480a2de84125910a70739a5"
            },
            {
              "fixed": "080695e6f005e2396f1207fd69d24c442cb230c6"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.9.0"
            },
            {
              "fixed": "6.12.103"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.44"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.1.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74543.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()\n\nsyzbot reported a memory leak [1] in the UDP tunnel NIC offload code.\n\nWhen device registration fails (e.g. in register_netdevice()), netdev core\nunwinds by sending a single NETDEV_UNREGISTER notification. If work was queued\nduring NETDEV_REGISTER (utn-\u003ework_pending is set), udp_tunnel_nic_unregister()\nreturns early:\n\n\tif (utn-\u003ework_pending)\n\t\treturn;\n\nBecause failed registrations do not enter netdev_wait_allrefs_any(), no\nsubsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the\nstruct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked\npermanently.\n\nFix this by removing the early return. Instead, synchronously cancel any\npending work with cancel_delayed_work_sync() before freeing @utn.\n\nTo be able to call cancel_delayed_work_sync() while holding RTNL (the work also\nneeds RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL\nis contended, requeue the work with a 1 jiffy delay (via queue_delayed_work())\nto prevent high CPU contention while waiting for RTNL lock.\n\nThe utn-\u003ework_pending bookkeeping is no longer needed and is removed, as\nthe workqueue core already tracks the pending/running state of the work.\n\n[1]\nBUG: memory leak\nunreferenced object 0xffff888127d5f840 (size 96):\n  comm \"syz-executor\", pid 5806, jiffies 4294942188\n  backtrace (crc 99fdb6c8):\n    __kmalloc_noprof+0x3bf/0x550\n    udp_tunnel_nic_alloc net/ipv4/udp_tunnel_nic.c:756 [inline]\n    udp_tunnel_nic_register net/ipv4/udp_tunnel_nic.c:833 [inline]\n    udp_tunnel_nic_netdevice_event+0x804/0xab0 net/ipv4/udp_tunnel_nic.c:931\n    notifier_call_chain+0x59/0x160 kernel/notifier.c:85\n    call_netdevice_notifiers_info+0x7d/0xb0 net/core/dev.c:2250\n    register_netdevice+0xc10/0xeb0 net/core/dev.c:11478",
  "id": "CVE-2026-74543",
  "modified": "2026-08-18T03:31:07.865341875Z",
  "published": "2026-08-15T12:27:53.336Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/080695e6f005e2396f1207fd69d24c442cb230c6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b322532a4b774db1b480a2de84125910a70739a5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b712da45bd9b9835d132e9fbc0c3e43c164cb1fd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f82a2ded3d7a9098267c84f14eafdb98c4550ac5"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74543.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74543"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()"
}