FastDDS's heap buffer overflow in RTPS DATA_FRAG enables unauthenticated DoS (potential RCE)

Fast DDS is a C++ implementation of the DDS (Data Distribution Service) standard of the OMG (Object Management Group
). Prior to versions 3.4.1, 3.3.1, and 2.6.11, a heap buffer overflow exists in the Fast-DDS DATA_FRAG receive path. An un
authenticated sender can transmit a single malformed RTPS DATA_FRAG packet where `fragmentSize` and `sampleSize` are craft
ed to violate internal assumptions. Due to a 4-byte alignment step during fragment metadata initialization, the code write
s past the end of the allocated payload buffer, causing immediate crash (DoS) and potentially enabling memory corruption (
RCE risk). Versions 3.4.1, 3.3.1, and 2.6.11 patch the issue.