Zephyr Project up to 4.3.0/4.4.1 L2CAP signaling l2cap_br.c l2cap_br_conf_req/l2cap_br_conf_rsp len memory corruption

Summaryinfo

A vulnerability identified as very critical has been detected in Zephyr Project Zephyr up to 4.3.0/4.4.1. This affects the function l2cap_br_conf_req/l2cap_br_conf_rsp of the file subsys/bluetooth/host/classic/l2cap_br.c of the component L2CAP signaling. This manipulation of the argument len causes memory corruption. This vulnerability appears as CVE-2026-10680. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Zephyr Project Zephyr up to 4.3.0/4.4.1. It has been declared as very critical. Affected by this vulnerability is the function l2cap_br_conf_req/l2cap_br_conf_rsp of the file subsys/bluetooth/host/classic/l2cap_br.c of the component L2CAP signaling. The manipulation of the argument len with an unknown input leads to a memory corruption vulnerability. The CWE definition for the vulnerability is CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE 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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-10680 since 06/02/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/22/2026).

Upgrading to version 4.3.1 eliminates this vulnerability. Applying the patch 1d451683377f4c8e56d7718565bea7b5c1155159 is able to eliminate this problem.

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Productinfo

Type

• Project Management Software

Vendor

• Zephyr Project

Name

• Zephyr

Version

• 4.0
• 4.1
• 4.2
• 4.3.0
• 4.4.0
• 4.4.1

CPE 2.3info

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CPE 2.2info

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