CVE-2026-10680

What it is

The Classic (BR/EDR) L2CAP signaling handlers l2cap_br_conf_req() and l2cap_br_conf_rsp() in subsys/bluetooth/host/classic/l2cap_br.c validated the minimum command size against buf->len (the bytes remaining in the whole received PDU) instead of len (the per-command data length from the L2CAP signaling header). Because multiple signaling commands can be packed into one PDU, buf->len may exceed a command's len. An attacker can send a CONF_REQ command with a header length smaller than the configuration-request structure (e.g. 0), followed by another command so that buf->len still satisfies the check. The check then passes incorrectly and opt_len = len - sizeof(*req) underflows the uint16_t to a near-0xFFFF value. The configuration-option loop, which lacks an opt_len-versus-buf->len guard, then walks far past the end of the pooled ACL receive buffer using net_buf pull primitives that perform no runtime bounds check, producing an out-of-bounds read of host memory and, when the out-of-bounds option bytes encode an MTU or flush-timeout option, an out-of-bounds write. The BR/EDR signaling channel is processed before pairing/encryption and an L2CAP channel to an L0 service such as SDP can be opened without pairing, so an unauthenticated peer within radio range that can establish an ACL connection can trigger the flaw, leading to memory corruption and denial of service (host/device crash). The defect is present in released versions including v4.4.0. The fix validates against len instead of buf->len in both handlers.

At a glance

Exploitability

Can be exploited from the same network segment without logging in. High risk of service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-21 22:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-24 19:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 7.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-07-21 22:17 UTC

Last modified

2026-10-24 19:10 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-125 · Out-of-bounds read

Record status

Analyzed

Affected

• Zephyrproject Zephyr < 4.3.1
• Zephyrproject Zephyr ≤ 4.4.1

Attack profile CVSS 3.1 · 7.6

Attack vector

Adjacent network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

High

Is it in your code?

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