CVE-2026-31393

/// Technical description

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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References