In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: validate connectionless PSM length Connectionless L2CAP frames carry a two-byte PSM at the start of the payload

Overview

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

Bluetooth: L2CAP: validate connectionless PSM length

Connectionless L2CAP frames carry a two-byte PSM at the start of the payload. l2cap_recv_frame() currently reads that PSM unconditionally after validating only the outer L2CAP length.

A malformed connectionless frame with a zero- or one-byte payload can therefore make the parser read beyond the advertised skb payload and use tailroom bytes as part of the PSM. A VHCI-backed QEMU reproducer injected a one-byte connectionless payload and reached the unchecked read.

Reject connectionless frames that cannot contain the PSM before reading or pulling it. This preserves all valid connectionless frames while dropping only structurally incomplete packets.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Vendor advisories

• Red Hat VEX · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-10-17 · vex