Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync hci_le_big_create_sync() uses DEFINE_FLEX to allocate a struct hci_cp_le_big_create_sync on the stack with room for 0x11 (17) BIS entries. However, conn->num_bis can hold up to HCI_MAX_ISO_BIS (31) entries — validated against ISO_MAX_NUM_BIS (0x1f) in the caller hci_conn_big_create_sync(). When conn->num_bis 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 bc_num_bis = ISO_MAX_NUM_BIS (31) and calling listen() will eventually trigger hci_le_big_create_sync() from the HCI command sync worker, causing a KASAN-detectable stack-out-of-bounds write: BUG: KASAN: stack-out-of-bounds in hci_le_big_create_sync+0x256/0x3b0 Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71 Fix this by changing the DEFINE_FLEX count from the incorrect 0x11 to HCI_MAX_ISO_BIS, which matches the maximum number of BIS entries that conn->bis can actually carry.
CVE-2026-31772
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-31772
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "91d19383b7ed035e22165ae5c836e50bb9f95fbe",
"lessThan": "f5d446624345d309e7a4a1b27ea9f028d6a8c5d9",
"versionType": "git"
},
{
"status": "affected",
"version": "42ecf1947135110ea08abeaca39741636f9a2285",
"lessThan": "aba0aea354015794e8312dd7efe726967e58aefe",
"versionType": "git"
},
{
"status": "affected",
"version": "42ecf1947135110ea08abeaca39741636f9a2285",
"lessThan": "eaf32002ca7b1ba51c9f140991fd9febe6de79f0",
"versionType": "git"
},
{
"status": "affected",
"version": "42ecf1947135110ea08abeaca39741636f9a2285",
"lessThan": "bc39a094730ce062fa034a529c93147c096cb488",
"versionType": "git"
},
{
"status": "affected",
"version": "8958e1cee4e2eac1a5b825caa4dd96ce9ed975dd",
"versionType": "git"
},
{
"status": "affected",
"version": "6.12.2",
"lessThan": "6.12.81",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.11.11",
"lessThan": "6.12",
"versionType": "semver"
}
],
"programFiles": [
"net/bluetooth/hci_sync.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.13"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.13",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.81",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.22",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "6.19.12",
"versionType": "semver",
"lessThanOrEqual": "6.19.*"
},
{
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/bluetooth/hci_sync.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-31772
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #39993 · Revision 1
- Added to Heist Feed
- Publisher date