In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hcisync: fix stack buffer overflow in hcilebigcreate_sync
hcilebigcreatesync() uses DEFINEFLEX to allocate a struct hcicplebigcreatesync on the stack with room for 0x11 (17) BIS entries. However, conn->numbis can hold up to HCIMAXISOBIS (31) entries — validated against ISOMAXNUMBIS (0x1f) in the caller hciconnbigcreatesync(). When conn->numbis is between 18 and 31, the memcpy that copies conn->bis into cp->bis writes up to 14 bytes past the stack buffer, corrupting adjacent stack memory.
This is trivially reproducible: binding an ISO socket with bcnumbis = ISOMAXNUMBIS (31) and calling listen() will eventually trigger hcilebigcreate_sync() from the HCI command sync worker, causing a KASAN-detectable stack-out-of-bounds write:
BUG: KASAN: stack-out-of-bounds in hcilebigcreatesync+0x256/0x3b0 Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71
Fix this by changing the DEFINEFLEX count from the incorrect 0x11 to HCIMAXISOBIS, which matches the maximum number of BIS entries that conn->bis can actually carry.
{
"cna_assigner": "Linux",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31772.json"
}