The Hierarchical Optimized Link State Routing (HOLSR) protocol was designed to improve scalability of heterogeneous Mobile Ad-Hoc Networks (MANETs). HOLSR is derived from the OLSR protocol and implements Multipoint Relay (MPR) nodes as a flooding mechanism for distributing control information. Unlike OLSR, nodes are organized in clusters and implement Hierarchical Topology Control (HTC) messages for inter-cluster communications. Nevertheless, HOLSR was designed without security measures. Therefore, a misbehaving node can affect the topology map acquisition process by interrupting the flooding of control information or disturbing the MPR selection process. We present a taxonomy of flooding disruption attacks, that affect the topology map acquisition process in HOLSR networks, and preventive mechanisms to mitigate the effect of this kind of attacks.