GHSA-GGHH-GC7F-JQCH
Vulnerability from github – Published: 2026-08-15 15:30 – Updated: 2026-08-19 18:32In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()
snd_usbmidi_akai_output() computes its fill-loop bound
buf_end = ep->max_transfer - MAX_AKAI_SYSEX_LEN - 1;
as a signed int, so a small device-advertised bulk-OUT max_transfer makes buf_end negative. The loop guard then compares the u32 urb->transfer_buffer_length against that negative int: the usual arithmetic conversion turns buf_end into a large unsigned value, so the guard stays true and each iteration keeps appending SysEx framing and payload bytes past the end of the URB transfer buffer, which is only max_transfer bytes long.
A USB device that advertises a tiny bulk-OUT endpoint can therefore trigger an attacker-length- and content-controlled heap out-of-bounds write when a process writes to the created /dev/snd/midiCD node.
Return early when there is no room for even one SysEx, so the loop is never entered with a bound that would wrap. The loop is the last statement of the function, so bailing out is equivalent to it not running.
Discovered by XBOW, triaged by Baul Lee baul.lee@xbow.com
{
"affected": [],
"aliases": [
"CVE-2026-74499"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T13:17:54Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()\n\nsnd_usbmidi_akai_output() computes its fill-loop bound\n\n\tbuf_end = ep-\u003emax_transfer - MAX_AKAI_SYSEX_LEN - 1;\n\nas a signed int, so a small device-advertised bulk-OUT max_transfer\nmakes buf_end negative. The loop guard then compares the u32\nurb-\u003etransfer_buffer_length against that negative int: the usual\narithmetic conversion turns buf_end into a large unsigned value, so the\nguard stays true and each iteration keeps appending SysEx framing and\npayload bytes past the end of the URB transfer buffer, which is only\nmax_transfer bytes long.\n\nA USB device that advertises a tiny bulk-OUT endpoint can therefore\ntrigger an attacker-length- and content-controlled heap out-of-bounds\nwrite when a process writes to the created /dev/snd/midiC*D* node.\n\nReturn early when there is no room for even one SysEx, so the loop is\nnever entered with a bound that would wrap. The loop is the last\nstatement of the function, so bailing out is equivalent to it not\nrunning.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e",
"id": "GHSA-gghh-gc7f-jqch",
"modified": "2026-08-19T18:32:29Z",
"published": "2026-08-15T15:30:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74499"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/00cc659a42ac4e94ec880fae2c9bf22fce69c2e8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0970274613fb463d376211450cab066d34ebfe6a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/29a4c29943631301e85f5e9d10f25741bd78e7ba"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2b7a0f330dd90dd1a7657cec0db019ee1efa4372"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/78dfdeb8d2065524ed5928d6470bf3d3244d1009"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9b22a5c8310b0d55d04f5f0159b913a2fb8b444f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b5305a0d0bb8e90a6fc9f88270d5f6c9b8c40081"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ce949d66607cfb000b8d8d84f80f35a886e72683"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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