Vulnerability-Lookup

CVE-2026-93186 (GCVE-0-2026-93186)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:12 – Updated: 2026-09-17 16:12

Title

cxl/mbox: Clamp mailbox output allocation to the payload size

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.

Severity

No CVSS data available.

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/f5d2bbf0300f46307…
https://git.kernel.org/stable/c/31d4841eca7c4b757…
https://git.kernel.org/stable/c/b4e11c731d6bee3b8…
https://git.kernel.org/stable/c/8a13db9f899d149c3…

Impacted products

2 products

Vendor	Product	Version	CPE status
Linux	Linux	Affected: 583fa5e71caeb79e04e477e9837e2f7fa53b71e4 , < f5d2bbf0300f46307948864fbb97bce5097f4fe2 (git) Affected: 583fa5e71caeb79e04e477e9837e2f7fa53b71e4 , < 31d4841eca7c4b75751ca96d24339e19303337f2 (git) Affected: 583fa5e71caeb79e04e477e9837e2f7fa53b71e4 , < b4e11c731d6bee3b87315e055a1ca417c92dc1fc (git) Affected: 583fa5e71caeb79e04e477e9837e2f7fa53b71e4 , < 8a13db9f899d149c3aab24abcb668121cfda5a4f (git)	guessed
Linux	Linux	Affected: 5.12 Unaffected: 0 , < 5.12 (semver) Unaffected: 6.12.110 , ≤ 6.12.* (semver) Unaffected: 6.18.52 , ≤ 6.18.* (semver) Unaffected: 7.2.6 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)	guessed

Show details on NVD website

JSON

To clipboard

{
  "containers": {
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      "affected": [
        {
          "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": [
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          ],
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.12"
            },
            {
              "lessThan": "5.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
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                  "versionStartIncluding": "5.12",
                  "vulnerable": true
                },
                {
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                },
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                },
                {
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                  "versionStartIncluding": "5.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-17T16:12:12.121Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2"
        },
        {
          "url": "https://git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2"
        },
        {
          "url": "https://git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc"
        },
        {
          "url": "https://git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f"
        }
      ],
      "title": "cxl/mbox: Clamp mailbox output allocation to the payload size",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93186",
    "datePublished": "2026-09-17T16:12:12.121Z",
    "dateReserved": "2026-09-17T16:02:15.091Z",
    "dateUpdated": "2026-09-17T16:12:12.121Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
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    "nvd": "{\"cve\":{\"id\":\"CVE-2026-93186\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-09-17T17:18:14.683\",\"lastModified\":\"2026-09-17T17:18:14.683\",\"vulnStatus\":\"Received\",\"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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/cxl/core/mbox.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"583fa5e71caeb79e04e477e9837e2f7fa53b71e4\",\"lessThan\":\"f5d2bbf0300f46307948864fbb97bce5097f4fe2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"583fa5e71caeb79e04e477e9837e2f7fa53b71e4\",\"lessThan\":\"31d4841eca7c4b75751ca96d24339e19303337f2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"583fa5e71caeb79e04e477e9837e2f7fa53b71e4\",\"lessThan\":\"b4e11c731d6bee3b87315e055a1ca417c92dc1fc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"583fa5e71caeb79e04e477e9837e2f7fa53b71e4\",\"lessThan\":\"8a13db9f899d149c3aab24abcb668121cfda5a4f\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/cxl/core/mbox.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.110\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.52\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.6\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"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\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}

FKIE_CVE-2026-93186

Vulnerability from fkie_nvd - Published: 2026-09-17 17:18 - Updated: 2026-09-17 17:18

Severity

Summary

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2

Impacted products

	Vendor	Product	Version

JSON

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"
}

GHSA-4XF9-VH86-48MC

Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-17 18:32

Details

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.

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-93186"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-17T17:18:14Z",
    "severity": null
  },
  "details": "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": "GHSA-4xf9-vh86-48mc",
  "modified": "2026-09-17T18:32:13Z",
  "published": "2026-09-17T18:32:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93186"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-93186 (GCVE-0-2026-93186)

FKIE_CVE-2026-93186

GHSA-4XF9-VH86-48MC

Tags

Sightings

Nomenclature

Related by attack behaviour