CVE-2026-31772

Advisory lineage Upstream: 0 Downstream: 6
Analyzed
Published: 01 May 2026, 14:15
Last modified:23 May 2026, 16:05

Vulnerability Summary

Overall Risk (default)
medium
31/100
CVSS Score
7.8 HIGH
v3.1 (cve.org)
EPSS Score
0.14% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

01 May 2026, 14:15
Published
Vulnerability first disclosed
23 May 2026, 16:05
Last Modified
Vulnerability information updated

Description

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.

CVSS Metrics

  • v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.14%• Percentile: 4%

Techniques & Countermeasures

  • CWE-787•Out-of-bounds Write

    The product writes data past the end, or before the beginning, of the intended buffer.

Affected Systems

  • linux•linux

    ≥ 91d19383b7ed035e22165ae5c836e50bb9f95fbe, < f5d446624345d309e7a4a1b27ea9f028d6a8c5d9 | ≥ 42ecf1947135110ea08abeaca39741636f9a2285, < aba0aea354015794e8312dd7efe726967e58aefe | ≥ 42ecf1947135110ea08abeaca39741636f9a2285, < eaf32002ca7b1ba51c9f140991fd9febe6de79f0 | ≥ 42ecf1947135110ea08abeaca39741636f9a2285, < bc39a094730ce062fa034a529c93147c096cb488 | 8958e1cee4e2eac1a5b825caa4dd96ce9ed975dd | ≥ 6.12.2, < 6.12.81 | ≥ 6.11.11, < 6.12 | 6.13

  • linux•linux kernel

    ≥ 6.11.11, < 6.12 | ≥ 6.12.2, < 6.12.81 | ≥ 6.13.1, < 6.18.22 | ≥ 6.19, < 6.19.12 | 6.13 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5 | 7.0:rc6

References (4)