CVE-2026-31513

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req

Syzbot reported a KASAN stack-out-of-bounds read in l2cap_build_cmd()

that is triggered by a malformed Enhanced Credit Based Connection Request.

The vulnerability stems from l2cap_ecred_conn_req(). The function allocates

a local stack buffer (`pdu`) designed to hold a maximum of 5 Source Channel

IDs (SCIDs), totaling 18 bytes. When an attacker sends a request with more

than 5 SCIDs, the function calculates `rsp_len` based on this unvalidated

`cmd_len` before checking if the number of SCIDs exceeds

L2CAP_ECRED_MAX_CID.

If the SCID count is too high, the function correctly jumps to the

`response` label to reject the packet, but `rsp_len` retains the

attacker's oversized value. Consequently, l2cap_send_cmd() is instructed

to read past the end of the 18-byte `pdu` buffer, triggering a

KASAN panic.

Fix this by moving the assignment of `rsp_len` to a

/// 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