An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6, affecting parse_group_prop_ntr_selection_method in lib/ofp-util.c. When decoding a group mod, it validates the group type and command after the whole group mod has been decoded. The OF1.5 decoder, however, tries to use the type and command earlier, when it might still be invalid. This causes an assertion failure (via OVS_NOT_REACHED). ovs-vswitchd does not enable support for OpenFlow 1.5 by default.
In lib/ofp-util.c in Open vSwitch (OvS) before 2.8.1, there are multiple memory leaks while parsing malformed OpenFlow group mod messages. NOTE: the vendor disputes the relevance of this report, stating "it can only be triggered by an OpenFlow controller, but OpenFlow controllers have much more direct and powerful ways to force Open vSwitch to allocate memory, such as by inserting flows into the flow table."