KernelScan.io

HIGH

bluetooth L2CAP OOB

CVE-2026-31393

CVSS 8.1 / 10.0 NVD

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

KernelScan AI7.1HIGH

01

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Validate L2CAP_INFO_RSP payload length before access l2cap_information_rsp() checks that cmd_len covers the fixed l2cap_info_rsp header (type + result, 4 bytes) but then reads rsp->data without verifying that the payload is present: - L2CAP_IT_FEAT_MASK calls get_unaligned_le32(rsp->data), which reads 4 bytes past the header (needs cmd_len >= 8). - L2CAP_IT_FIXED_CHAN reads rsp->data[0], 1 byte past the header (needs cmd_len >= 5). A truncated L2CAP_INFO_RSP with result == L2CAP_IR_SUCCESS triggers an out-of-bounds read of adjacent skb data. Guard each data access with the required payload length check. If the payload is too short, skip the read and let the state machine complete with safe defaults (feat_mask and remote_fixed_chan remain zero from kzalloc), so the info timer cleanup and l2cap_conn_start() still run and the connection is not stalled.

02

Engine v0.2.0

Risk summary

Bluetooth-enabled devices are vulnerable to denial-of-service attacks and limited information disclosure from nearby attackers. Malformed L2CAP packets during connection setup can cause kernel crashes or leak adjacent kernel memory contents.

Affectednet/bluetooth/l2cap_core.c (Bluetooth L2CAP)

Vulnerability analysis

The l2cap_information_rsp() function validates the L2CAP_INFO_RSP header length but fails to verify payload size before reading rsp->data. This allows truncated packets with result=L2CAP_IR_SUCCESS to trigger out-of-bounds reads of 1-4 bytes into adjacent skb data. The fix adds proper length checks before each data access, falling back to safe zero defaults when payload is insufficient. Attack surface is adjacent network (Bluetooth radio range) with no authentication required.

03

BranchFixed inPatch commit
5.105.10.253187e6fe93929
5.155.15.2035229e7d15771
6.16.1.1673b646516cba2
6.126.12.789aeacde4da0f
6.186.18.20e7ff754e339e
6.196.19.10db2872d054e4
6.66.6.130807bd1258453
mainline7.0dd815e6e3918