Bluetooth Key Size Validation Flaw in Linux Kernel

Publication date: 2026-05-06

Last updated on: 2026-05-08

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix missing key size check for L2CAP_LE_CONN_REQ This adds a check for encryption key size upon receiving L2CAP_LE_CONN_REQ which is required by L2CAP/LE/CFC/BV-15-C which expects L2CAP_CR_LE_BAD_KEY_SIZE.

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Meta Information

Published

2026-05-06

Last Modified

2026-05-08

Generated

2026-07-06

AI Q&A

2026-05-06

EPSS Evaluated

2026-07-05

NVD

CVE-2026-43134

EUVD

EUVD-2026-27694

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability is in the Linux kernel's Bluetooth component, specifically related to L2CAP (Logical Link Control and Adaptation Protocol). It involves a missing check for the encryption key size when processing L2CAP_LE_CONN_REQ (a connection request). The fix adds this key size check, which is required by the L2CAP/LE/CFC/BV-15-C specification and expects a specific error code (L2CAP_CR_LE_BAD_KEY_SIZE) if the key size is invalid.

Impact Analysis

Without the key size check, an attacker might be able to establish a Bluetooth connection using an encryption key that is too small or otherwise invalid, potentially weakening the security of the Bluetooth communication. This could lead to unauthorized access or interception of data transmitted over Bluetooth.

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