{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "998f70d1806bb718a7565f350283e4a79c8cbb4b"
            },
            {
              "fixed": "0b6680e306397097a97767447368221fac753809"
            },
            {
              "fixed": "8391ee06d08845a0a165b5fe679ba326915166b2"
            },
            {
              "fixed": "47504742cea7878ebd1bf1491bbed923df6b90b1"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.14.0"
            },
            {
              "fixed": "6.18.51"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80975.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmfd: qnap-mcu: keep the reply buffer alive past a command timeout\n\nqnap_mcu_exec() publishes an on-stack buffer to the receive path:\n\n\tunsigned char rx[QNAP_MCU_RX_BUFFER_SIZE];\n\t...\n\treply-\u003edata = rx;\n\treply-\u003elength = length;\n\nand qnap_mcu_receive_buf() writes into it from the serdev receive path,\nwhich runs out of flush_to_ldisc() and is not serialized against\nqnap_mcu_exec() at all. bus_lock cannot cover it, because qnap_mcu_exec()\nholds that mutex across wait_for_completion_timeout().\n\nOn a timeout qnap_mcu_exec() returns with reply-\u003edata still pointing at\nits own frame. A reply that arrives late, or an unsolicited message from\nthe MCU, is then written into a stack frame that has been left, corrupting\nwhatever runs next on that stack. The same applies when qnap_mcu_write()\nfails, since that path returns without touching the reply state either.\n\nMove the receive buffer into struct qnap_mcu. It is 37 bytes and the\nstructure is devm_kzalloc()ed, so it lives as long as the driver, and a\nlate write lands in memory that is still valid and is reinitialized by the\nnext command. bus_lock keeps commands from sharing it.\n\nThis deliberately does not clear reply-\u003edata or reply-\u003elength on the\ntimeout path. Doing so races with qnap_mcu_receive_buf(), which reads both\nafter its\n\n\tif (!reply-\u003elength)\n\t\treturn size;\n\ncheck: clearing reply-\u003edata gives a NULL dereference, and clearing\nreply-\u003elength alone removes the reply-\u003ereceived == reply-\u003elength exit\ncondition, so the copy loop runs until the uart chunk is consumed and\noverruns the buffer. Leaving both set keeps the write bounded by\nreply-\u003elength, which qnap_mcu_exec() has already checked against\nsizeof(mcu-\u003erx).",
  "id": "CVE-2026-80975",
  "modified": "2026-09-15T03:30:24.524422210Z",
  "published": "2026-09-11T19:42:37.086Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0b6680e306397097a97767447368221fac753809"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/47504742cea7878ebd1bf1491bbed923df6b90b1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8391ee06d08845a0a165b5fe679ba326915166b2"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80975.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80975"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "mfd: qnap-mcu: keep the reply buffer alive past a command timeout"
}