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Versions Affected : All verisons prior to FreeNAS 11.3-U5


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.


No workaround is available.


  • Upgrade to FreeNAS 11.3-U5 or later.


Further information