{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "67737c457281dd199ceb9e31b6ba7efd3bfe566d"
            },
            {
              "fixed": "47893166bc5611ee9a20de6b8d2933b2320fb772"
            },
            {
              "fixed": "86f5334fcb48a5b611c33364ab52ca684d0f6d91"
            },
            {
              "fixed": "0695712f3a6f1a48915f95767cfb42077683dcdc"
            },
            {
              "fixed": "925a5ffd99cddd7a7e41d5ad120c7a2c6d50260f"
            },
            {
              "fixed": "8d27d9b260dd19c1b519e1a13de6448f9984e30e"
            },
            {
              "fixed": "7d86aa41c073c4e7eb75fd2e674f1fd8f289728a"
            }
          ],
          "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": "6.1.167"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.130"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.78"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.19"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43455.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmctp: route: hold key-\u003elock in mctp_flow_prepare_output()\n\nmctp_flow_prepare_output() checks key-\u003edev and may call\nmctp_dev_set_key(), but it does not hold key-\u003elock while doing so.\n\nmctp_dev_set_key() and mctp_dev_release_key() are annotated with\n__must_hold(\u0026key-\u003elock), so key-\u003edev access is intended to be\nserialized by key-\u003elock. The mctp_sendmsg() transmit path reaches\nmctp_flow_prepare_output() via mctp_local_output() -\u003e mctp_dst_output()\nwithout holding key-\u003elock, so the check-and-set sequence is racy.\n\nExample interleaving:\n\n  CPU0                                  CPU1\n  ----                                  ----\n  mctp_flow_prepare_output(key, devA)\n    if (!key-\u003edev)  // sees NULL\n                                        mctp_flow_prepare_output(\n                                            key, devB)\n                                          if (!key-\u003edev)  // still NULL\n                                          mctp_dev_set_key(devB, key)\n                                            mctp_dev_hold(devB)\n                                            key-\u003edev = devB\n    mctp_dev_set_key(devA, key)\n      mctp_dev_hold(devA)\n      key-\u003edev = devA   // overwrites devB\n\nNow both devA and devB references were acquired, but only the final\nkey-\u003edev value is tracked for release. One reference can be lost,\ncausing a resource leak as mctp_dev_release_key() would only decrease\nthe reference on one dev.\n\nFix by taking key-\u003elock around the key-\u003edev check and\nmctp_dev_set_key() call.",
  "id": "CVE-2026-43455",
  "modified": "2026-07-15T01:49:20.669650486Z",
  "published": "2026-05-08T14:22:19.375Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0695712f3a6f1a48915f95767cfb42077683dcdc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/47893166bc5611ee9a20de6b8d2933b2320fb772"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7d86aa41c073c4e7eb75fd2e674f1fd8f289728a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/86f5334fcb48a5b611c33364ab52ca684d0f6d91"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8d27d9b260dd19c1b519e1a13de6448f9984e30e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/925a5ffd99cddd7a7e41d5ad120c7a2c6d50260f"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43455.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43455"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "summary": "mctp: route: hold key-\u003elock in mctp_flow_prepare_output()"
}