{"id":"CVE-2026-31772","summary":"Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync\n\nhci_le_big_create_sync() uses DEFINE_FLEX to allocate a\nstruct hci_cp_le_big_create_sync on the stack with room for 0x11 (17)\nBIS entries.  However, conn-\u003enum_bis can hold up to HCI_MAX_ISO_BIS (31)\nentries — validated against ISO_MAX_NUM_BIS (0x1f) in the caller\nhci_conn_big_create_sync().  When conn-\u003enum_bis is between 18 and 31,\nthe memcpy that copies conn-\u003ebis into cp-\u003ebis writes up to 14 bytes\npast the stack buffer, corrupting adjacent stack memory.\n\nThis is trivially reproducible: binding an ISO socket with\nbc_num_bis = ISO_MAX_NUM_BIS (31) and calling listen() will\neventually trigger hci_le_big_create_sync() from the HCI command\nsync worker, causing a KASAN-detectable stack-out-of-bounds write:\n\n  BUG: KASAN: stack-out-of-bounds in hci_le_big_create_sync+0x256/0x3b0\n  Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71\n\nFix this by changing the DEFINE_FLEX count from the incorrect 0x11 to\nHCI_MAX_ISO_BIS, which matches the maximum number of BIS entries that\nconn-\u003ebis can actually carry.","modified":"2026-10-28T02:31:01.646119282Z","published":"2026-05-01T14:15:00.582Z","related":["ALSA-2026:27288","ALSA-2026:27789","SUSE-SU-2026:23066-1","SUSE-SU-2026:23068-1","SUSE-SU-2026:23221-1","SUSE-SU-2026:23231-1","SUSE-SU-2026:23237-1","openSUSE-SU-2026:21555-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31772.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/aba0aea354015794e8312dd7efe726967e58aefe"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bc39a094730ce062fa034a529c93147c096cb488"},{"type":"WEB","url":"https://git.kernel.org/stable/c/eaf32002ca7b1ba51c9f140991fd9febe6de79f0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f5d446624345d309e7a4a1b27ea9f028d6a8c5d9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31772.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31772"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"91d19383b7ed035e22165ae5c836e50bb9f95fbe"},{"fixed":"f5d446624345d309e7a4a1b27ea9f028d6a8c5d9"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"42ecf1947135110ea08abeaca39741636f9a2285"},{"fixed":"aba0aea354015794e8312dd7efe726967e58aefe"},{"fixed":"eaf32002ca7b1ba51c9f140991fd9febe6de79f0"},{"fixed":"bc39a094730ce062fa034a529c93147c096cb488"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.12.2"},{"fixed":"6.12.81"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.11.11"},{"fixed":"6.12"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8958e1cee4e2eac1a5b825caa4dd96ce9ed975dd"}]}],"versions":["v6.12.80","v6.12.79","v6.12.78","v6.12.77","v6.12.76","v6.12.75","v6.12.74","v6.12.73","v6.12.72","v6.12.71","v6.12.70","v6.12.69","v6.12.68","v6.12.67","v6.12.66","v6.12.65","v6.12.64","v6.12.63","v6.12.62","v6.12.61","v6.12.60","v6.12.59","v6.12.58","v6.12.57","v6.12.56","v6.12.55","v6.12.54","v6.12.53","v6.12.52","v6.12.51","v6.12.50","v6.12.49","v6.12.48","v6.12.47","v6.12.46","v6.12.45","v6.12.44","v6.12.43","v6.12.42","v6.12.41","v6.12.40","v6.12.39","v6.12.38","v6.12.37","v6.12.36","v6.12.35","v6.12.34","v6.12.33","v6.12.32","v6.12.31","v6.12.30","v6.12.29","v6.12.28","v6.12.27","v6.12.26","v6.12.25","v6.12.24","v6.12.23","v6.12.22","v6.12.21","v6.12.20","v6.12.19","v6.12.18","v6.12.17","v6.12.16","v6.12.15","v6.12.14","v6.12.13","v6.12.12","v6.12.11","v6.12.10","v6.12.9","v6.12.8","v6.12.7","v6.12.6","v6.12.5","v6.12.4","v6.12.3","v6.12.2","v6.11.11"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-31772.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.81"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.22"},{"fixed":"6.19.12"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-31772.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}