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.