{"cve":"CVE-2026-43455","nvd":{"published":"2026-05-08T15:16:58.263","modified":"2026-06-17T10:49:38.050","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmctp: route: hold key->lock in mctp_flow_prepare_output()\n\nmctp_flow_prepare_output() checks key->dev and may call\nmctp_dev_set_key(), but it does not hold key->lock while doing so.\n\nmctp_dev_set_key() and mctp_dev_release_key() are annotated with\n__must_hold(&key->lock), so key->dev access is intended to be\nserialized by key->lock. The mctp_sendmsg() transmit path reaches\nmctp_flow_prepare_output() via mctp_local_output() -> mctp_dst_output()\nwithout holding key->lock, 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->dev)  // sees NULL\n                                        mctp_flow_prepare_output(\n                                            key, devB)\n                                          if (!key->dev)  // still NULL\n                                          mctp_dev_set_key(devB, key)\n                                            mctp_dev_hold(devB)\n                                            key->dev = devB\n    mctp_dev_set_key(devA, key)\n      mctp_dev_hold(devA)\n      key->dev = devA   // overwrites devB\n\nNow both devA and devB references were acquired, but only the final\nkey->dev 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->lock around the key->dev check and\nmctp_dev_set_key() call.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/0695712f3a6f1a48915f95767cfb42077683dcdc","https://git.kernel.org/stable/c/47893166bc5611ee9a20de6b8d2933b2320fb772","https://git.kernel.org/stable/c/7d86aa41c073c4e7eb75fd2e674f1fd8f289728a","https://git.kernel.org/stable/c/86f5334fcb48a5b611c33364ab52ca684d0f6d91","https://git.kernel.org/stable/c/8d27d9b260dd19c1b519e1a13de6448f9984e30e"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:33:55.586217763+00:00"},"epss":{"cve":"CVE-2026-43455","score":0.00114,"percentile":0.01475,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}