l2tp: Fix memleak in l2tp_udp_encap_recv().

{
  "id": "38454b695880aef204d798ea6eef27f2bce7bfd3129d3ab78179feb4e396d872",
  "url": "https://osv.dev/vulnerability/CVE-2026-23072",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "l2tp: Fix memleak in l2tp_udp_encap_recv().",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: l2tp: Fix memleak in l2tp_udp_encap_recv(). syzbot reported memleak of struct l2tp_session, l2tp_tunnel, sock, etc. [0] The cited commit moved down the validation of the protocol version in l2tp_udp_encap_recv(). The new place requires an extra error handling to avoid the memleak. Let's call l2tp_session_put() there. [0]: BUG: memory leak unreferenced object 0xffff88810a290200 (size 512): comm \"syz.0.17\", pid 6086, jiffies 4294944299 hex dump (first 32 bytes): 7d eb 04 0c 00 00 00 00 01 00 00 00 00 00 00 00 }............... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc babb6a4f): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4958 [inline] slab_alloc_node mm/slub.c:5263 [inline] __do_kmalloc_node mm/slub.c:5656 [inline] __kmalloc_noprof+0x3e0/0x660 mm/slub.c:5669 kmalloc_noprof include/linux/slab.h:961 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] l2tp_session_create+0x3a/0x3b0 net/l2tp/l2tp_core.c:1778 pppol2tp_connect+0x48b/0x920 net/l2tp/l2tp_ppp.c:755 __sys_connect_file+0x7a/0xb0 net/socket.c:2089 __sys_connect+0xde/0x110 net/socket.c:2108 __do_sys_connect net/socket.c:2114 [inline] __se_sys_connect net/socket.c:2111 [inline] __x64_sys_connect+0x1c/0x30 net/socket.c:2111 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x7",
    "evidence": "osv:CVE-2026-23072",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.68",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-23072",
      "aliases": [
        "CVE-2026-23072"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "364798056f518b0bf2f17cd9eaf0dd4e856d7393"
                },
                {
                  "fixed": "5cd158a88eef34e7b100cd9b963873d3b4e41b35"
                },
                {
                  "fixed": "d4ce79e6dce2a4a49eebceea7b4caf5dc0f0ef3d"
                },
                {
                  "fixed": "4d10edfd1475b69dbd4c47f34b61a3772ece83ca"
                }
              ]
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23072.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.10.0"
                },
                {
                  "fixed": "6.12.68"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.8"
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              ]
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23072.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.163464872Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/4d10edfd1475b69dbd4c47f34b61a3772ece83ca",
        "https://git.kernel.org/stable/c/5cd158a88eef34e7b100cd9b963873d3b4e41b35",
        "https://git.kernel.org/stable/c/d4ce79e6dce2a4a49eebceea7b4caf5dc0f0ef3d",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23072.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-23072",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23072.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-23072",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 501248,
  "published_at": "2026-02-04T16:07:52.79+00:00"
}