GHSA-4HX3-PX5F-MCX4
Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30In the Linux kernel, the following vulnerability has been resolved:
HID: wacom: fix slab-out-of-bounds write in wacom_wac_queue_insert
wacom_wac_queue_insert() calls kfifo_skip() in a loop when the kfifo doesn't have enough space for the incoming report. If the kfifo is empty, kfifo_skip() reads stale data left in the kmalloc'd buffer via __kfifo_peek_n() and interprets it as a record length, advancing fifo->out by that garbage value. This corrupts the internal kfifo state, causing kfifo_unused() to return a value much larger than the actual buffer size, which bypasses __kfifo_in_r()'s guard:
if (len + recsize > kfifo_unused(fifo)) return 0;
kfifo_copy_in() then performs an out-of-bounds memcpy, writing up to 3842 bytes past the 256-byte buffer.
Add a !kfifo_is_empty() condition to the while loop so kfifo_skip() is never called on an empty fifo, and check the return value of kfifo_in() to reject reports that are too large for the fifo.
{
"affected": [],
"aliases": [
"CVE-2026-64366"
],
"database_specific": {
"cwe_ids": [
"CWE-787"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-25T10:17:19Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nHID: wacom: fix slab-out-of-bounds write in wacom_wac_queue_insert\n\nwacom_wac_queue_insert() calls kfifo_skip() in a loop when the kfifo\ndoesn\u0027t have enough space for the incoming report. If the kfifo is\nempty, kfifo_skip() reads stale data left in the kmalloc\u0027d buffer\nvia __kfifo_peek_n() and interprets it as a record length, advancing\nfifo-\u003eout by that garbage value. This corrupts the internal kfifo\nstate, causing kfifo_unused() to return a value much larger than the\nactual buffer size, which bypasses __kfifo_in_r()\u0027s guard:\n\n if (len + recsize \u003e kfifo_unused(fifo))\n return 0;\n\nkfifo_copy_in() then performs an out-of-bounds memcpy, writing up to\n3842 bytes past the 256-byte buffer.\n\nAdd a !kfifo_is_empty() condition to the while loop so kfifo_skip()\nis never called on an empty fifo, and check the return value of\nkfifo_in() to reject reports that are too large for the fifo.",
"id": "GHSA-4hx3-px5f-mcx4",
"modified": "2026-07-27T06:30:34Z",
"published": "2026-07-25T12:31:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64366"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/57bdd10ad50d68341f500a7b330f0d8949e510ec"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6b3014ec0e9a390ca563030b2d7689921f0daef5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ca899a926c11a59211b764b0155d9a1cdcc32b81"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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