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FKIE_CVE-2026-93186

Vulnerability from fkie_nvd - Published: 2026-09-17 17:18 - Updated: 2026-09-17 17:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: cxl/mbox: Clamp mailbox output allocation to the payload size CXL_MEM_SEND_COMMAND bounds the user's in.size to the mailbox payload size but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls kvzalloc(out.size). A large out.size drives a huge allocation, above INT_MAX it WARNs and taints, and with panic_on_warn=1 it panics. The transport __cxl_pci_mbox_send_cmd() already clamps the response copy to min(out.size, payload_size, device len), so the output buffer is never written beyond payload_size. Clamp the allocation to payload_size too, matching the RAW path.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/cxl/core/mbox.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f5d2bbf0300f46307948864fbb97bce5097f4fe2",
              "status": "affected",
              "version": "583fa5e71caeb79e04e477e9837e2f7fa53b71e4",
              "versionType": "git"
            },
            {
              "lessThan": "31d4841eca7c4b75751ca96d24339e19303337f2",
              "status": "affected",
              "version": "583fa5e71caeb79e04e477e9837e2f7fa53b71e4",
              "versionType": "git"
            },
            {
              "lessThan": "b4e11c731d6bee3b87315e055a1ca417c92dc1fc",
              "status": "affected",
              "version": "583fa5e71caeb79e04e477e9837e2f7fa53b71e4",
              "versionType": "git"
            },
            {
              "lessThan": "8a13db9f899d149c3aab24abcb668121cfda5a4f",
              "status": "affected",
              "version": "583fa5e71caeb79e04e477e9837e2f7fa53b71e4",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/cxl/core/mbox.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.12"
            },
            {
              "lessThan": "5.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncxl/mbox: Clamp mailbox output allocation to the payload size\n\nCXL_MEM_SEND_COMMAND bounds the user\u0027s in.size to the mailbox payload\nsize but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls\nkvzalloc(out.size). A large out.size drives a huge allocation, above\nINT_MAX it WARNs and taints, and with panic_on_warn=1 it panics.\n\nThe transport __cxl_pci_mbox_send_cmd() already clamps the response copy\nto min(out.size, payload_size, device len), so the output buffer is\nnever written beyond payload_size. Clamp the allocation to payload_size\ntoo, matching the RAW path."
    }
  ],
  "id": "CVE-2026-93186",
  "lastModified": "2026-09-17T17:18:14.683",
  "metrics": {},
  "published": "2026-09-17T17:18:14.683",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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