{
  "containers": {
    "adp": [
      {
        "affected": [
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-08T08:46:17.289Z",
          "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
          "shortName": "siemens-SADP"
        },
        "references": [
          {
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
          },
          {
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
          }
        ],
        "x_adpType": "supplier"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/smc/af_smc.c",
            "net/smc/smc.h",
            "net/smc/smc_close.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f315277856caeafcd996c2611afc085ca2d53275",
              "status": "affected",
              "version": "ebfee3e153f67c8b38eb94a7062ee94aa6f92708",
              "versionType": "git"
            },
            {
              "lessThan": "1e4f873879e075bbd4eb1c644d6933303ac5eba4",
              "status": "affected",
              "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
              "versionType": "git"
            },
            {
              "lessThan": "f00fc26c8a06442b225a350fe000c0a11483e6a3",
              "status": "affected",
              "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
              "versionType": "git"
            },
            {
              "lessThan": "cadf3da46c15523fba90d80c9955f536ee3b4023",
              "status": "affected",
              "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
              "versionType": "git"
            },
            {
              "lessThan": "fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2",
              "status": "affected",
              "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
              "versionType": "git"
            },
            {
              "lessThan": "1fab5ece76fb42a761178dcd0ebcbf578377b0dd",
              "status": "affected",
              "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
              "versionType": "git"
            },
            {
              "lessThan": "6d5e4538364b9ceb1ac2941a4deb86650afb3538",
              "status": "affected",
              "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
              "versionType": "git"
            },
            {
              "lessThan": "5.15.203",
              "status": "affected",
              "version": "5.15.174",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/smc/af_smc.c",
            "net/smc/smc.h",
            "net/smc/smc_close.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.18"
            },
            {
              "lessThan": "5.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.203",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.167",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.130",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.20",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.203",
                  "versionStartIncluding": "5.15.174",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.167",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.130",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.78",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.20",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.10",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()\n\nSyzkaller reported a panic in smc_tcp_syn_recv_sock() [1].\n\nsmc_tcp_syn_recv_sock() is called in the TCP receive path\n(softirq) via icsk_af_ops-\u003esyn_recv_sock on the clcsock (TCP\nlistening socket). It reads sk_user_data to get the smc_sock\npointer. However, when the SMC listen socket is being closed\nconcurrently, smc_close_active() sets clcsock-\u003esk_user_data\nto NULL under sk_callback_lock, and then the smc_sock itself\ncan be freed via sock_put() in smc_release().\n\nThis leads to two issues:\n\n1) NULL pointer dereference: sk_user_data is NULL when\n   accessed.\n2) Use-after-free: sk_user_data is read as non-NULL, but the\n   smc_sock is freed before its fields (e.g., queued_smc_hs,\n   ori_af_ops) are accessed.\n\nThe race window looks like this (the syzkaller crash [1]\ntriggers via the SYN cookie path: tcp_get_cookie_sock() -\u003e\nsmc_tcp_syn_recv_sock(), but the normal tcp_check_req() path\nhas the same race):\n\n  CPU A (softirq)              CPU B (process ctx)\n\n  tcp_v4_rcv()\n    TCP_NEW_SYN_RECV:\n    sk = req-\u003ersk_listener\n    sock_hold(sk)\n    /* No lock on listener */\n                               smc_close_active():\n                                 write_lock_bh(cb_lock)\n                                 sk_user_data = NULL\n                                 write_unlock_bh(cb_lock)\n                                 ...\n                                 smc_clcsock_release()\n                                 sock_put(smc-\u003esk) x2\n                                   -\u003e smc_sock freed!\n    tcp_check_req()\n      smc_tcp_syn_recv_sock():\n        smc = user_data(sk)\n          -\u003e NULL or dangling\n        smc-\u003equeued_smc_hs\n          -\u003e crash!\n\nNote that the clcsock and smc_sock are two independent objects\nwith separate refcounts. TCP stack holds a reference on the\nclcsock, which keeps it alive, but this does NOT prevent the\nsmc_sock from being freed.\n\nFix this by using RCU and refcount_inc_not_zero() to safely\naccess smc_sock. Since smc_tcp_syn_recv_sock() is called in\nthe TCP three-way handshake path, taking read_lock_bh on\nsk_callback_lock is too heavy and would not survive a SYN\nflood attack. Using rcu_read_lock() is much more lightweight.\n\n- Set SOCK_RCU_FREE on the SMC listen socket so that\n  smc_sock freeing is deferred until after the RCU grace\n  period. This guarantees the memory is still valid when\n  accessed inside rcu_read_lock().\n- Use rcu_read_lock() to protect reading sk_user_data.\n- Use refcount_inc_not_zero(\u0026smc-\u003esk.sk_refcnt) to pin the\n  smc_sock. If the refcount has already reached zero (close\n  path completed), it returns false and we bail out safely.\n\nNote: smc_hs_congested() has a similar lockless read of\nsk_user_data without rcu_read_lock(), but it only checks for\nNULL and accesses the global smc_hs_wq, never dereferencing\nany smc_sock field, so it is not affected.\n\nReproducer was verified with mdelay injection and smc_run,\nthe issue no longer occurs with this patch applied.\n\n[1] https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable callback is invoked from the TCP receive path via tcp_check_req() or tcp_get_cookie_sock() for packets hitting an SMC listening socket. A remote peer can reach this pre-authentication code by completing or racing TCP handshakes to the exposed listener.\nAC:L - The trigger is a close-vs-handshake race, but the attacker can drive the packet side repeatedly with concurrent connection attempts and SYN-cookie/normal ACK paths. There is no rare memory layout, special authentication state, or non-default runtime condition required beyond an enabled SMC listener.\nPR:N - No kernel capability, local account, or SMC protocol authentication is checked before smc_tcp_syn_recv_sock() dereferences sk_user_data. The network peer reaches the vulnerable path before accept-time SMC CLC processing.\nUI:N - Exploitation does not require a victim user action once an SMC listener is present. Incoming network traffic and concurrent listener teardown are sufficient to hit the vulnerable path.\nS:U - The bug corrupts or crashes kernel state within the same host security authority. It is not a VM escape, IOMMU bypass, or cross-scope boundary violation.\nC:H - The fix addresses a real use-after-free of struct smc_sock, not only a NULL dereference. Under the required kernel guidance, UAF is treated as enabling high confidentiality impact through potential reuse and disclosure primitives.\nI:H - The dangling smc_sock is dereferenced for fields including queued_smc_hs and ori_af_ops, and UAF of kernel heap objects can be shaped into control-flow or write primitives. Under the required kernel guidance, UAF warrants high integrity impact.\nA:H - The observed failure is a KASAN NULL dereference/oops in smc_tcp_syn_recv_sock(), and the UAF path can also crash the kernel. Kernel oops or panic is high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:21:50.884Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f315277856caeafcd996c2611afc085ca2d53275"
        },
        {
          "url": "https://git.kernel.org/stable/c/1e4f873879e075bbd4eb1c644d6933303ac5eba4"
        },
        {
          "url": "https://git.kernel.org/stable/c/f00fc26c8a06442b225a350fe000c0a11483e6a3"
        },
        {
          "url": "https://git.kernel.org/stable/c/cadf3da46c15523fba90d80c9955f536ee3b4023"
        },
        {
          "url": "https://git.kernel.org/stable/c/fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2"
        },
        {
          "url": "https://git.kernel.org/stable/c/1fab5ece76fb42a761178dcd0ebcbf578377b0dd"
        },
        {
          "url": "https://git.kernel.org/stable/c/6d5e4538364b9ceb1ac2941a4deb86650afb3538"
        }
      ],
      "title": "net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23450",
    "datePublished": "2026-04-03T15:15:33.144Z",
    "dateReserved": "2026-01-13T15:37:46.020Z",
    "dateUpdated": "2026-09-08T08:46:17.289Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}