FreeBSD VuXML: Documenting security issues in FreeBSD and the FreeBSD Ports Collection

FreeBSD -- ure device driver susceptible to packet-in-packet attack

Affected packages
12.1 <= FreeBSD-kernel < 12.1_10
11.4 <= FreeBSD-kernel < 11.4_4
11.3 <= FreeBSD-kernel < 11.3_14


VuXML ID bb53af7b-f7e4-11ea-88f8-901b0ef719ab
Discovery 2020-09-15
Entry 2020-09-16

Problem Description:

A programming error in the ure(4) device driver caused some Realtek USB Ethernet interfaces to incorrectly report packets with more than 2048 bytes in a single USB transfer as having a length of only 2048 bytes.

An adversary can exploit this to cause the driver to misinterpret part of the payload of a large packet as a separate packet, and thereby inject packets across security boundaries such as VLANs.


An attacker that can send large frames (larger than 2048 bytes in size) to be received by the host (be it VLAN, or non-VLAN tagged packet), can inject arbitrary packets to be received and processed by the host. This includes spoofing packets from other hosts, or injecting packets to other VLANs than the host is on.


CVE Name CVE-2020-7464
FreeBSD Advisory SA-20:27.ure