{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "92c025db52bb94a032eb3d473bb81e62c19ddbd3"
            },
            {
              "fixed": "2c09cadec116eba3fdbcb5d8d8641f6777d4a11f"
            },
            {
              "fixed": "1b0a3d915320f1600e5ff43f8bc21b73118480b8"
            },
            {
              "fixed": "3921bb8635ff2836622df1cdf3194d4f3c1835a4"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.16.0"
            },
            {
              "fixed": "6.18.52"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90136.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86/amd/hsmp: Reject negative power cap writes in hwmon\n\nhsmp_hwmon_write() takes the user-supplied hwmon value as a signed long\nand assigns \"val / MICROWATT_PER_MILLIWATT\" to msg.args[0], which is a\n__u32.  MICROWATT_PER_MILLIWATT is an unsigned long, so a negative write\nto power1_cap (e.g. \"echo -1 \u003e power1_cap\") is first converted to a huge\nunsigned value by the division and then stored into the u32 argument.\n\nAs a result a nonsensical, multi-gigawatt socket power limit is sent to\nthe SMU via HSMP_SET_SOCKET_POWER_LIMIT instead of the write being\nrejected.\n\nReject negative values with -EINVAL before the conversion.\n\nTested with HSMP enabled:\n\n  CAP=$(dirname $(grep -l amd_hsmp_hwmon \\\n        /sys/class/hwmon/hwmon*/name | head -1))/power1_cap\n\n  # negative write\n  echo -1000000 \u003e $CAP ; echo \"ret=$?\"\n  # valid positive write must still work\n  echo 400000000 \u003e $CAP ; echo \"ret=$?\"\n\nBefore:\n  # echo -1000000 \u003e $CAP ; echo \"ret=$?\"\n  ret=0                             \u003c- accepted; bogus limit sent to SMU\n  # echo 400000000 \u003e $CAP ; echo \"ret=$?\"\n  ret=0\n\nAfter:\n  # echo -1000000 \u003e $CAP ; echo \"ret=$?\"\n  bash: echo: write error: Invalid argument\n  ret=1                             \u003c- rejected with -EINVAL\n  # echo 400000000 \u003e $CAP ; echo \"ret=$?\"\n  ret=0                             \u003c- valid write still works",
  "id": "CVE-2026-90136",
  "modified": "2026-09-18T03:30:31.477313435Z",
  "published": "2026-09-17T16:06:35.190Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1b0a3d915320f1600e5ff43f8bc21b73118480b8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2c09cadec116eba3fdbcb5d8d8641f6777d4a11f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3921bb8635ff2836622df1cdf3194d4f3c1835a4"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90136.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90136"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "platform/x86/amd/hsmp: Reject negative power cap writes in hwmon"
}