GHSA-4XF9-VH86-48MC
Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-17 18:32In 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.
{
"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": []
}
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