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, when the security mode is enabled, modifying the DATA Submessage within an SPDP packet sent by a publisher causes a heap buffer overflow, resulting in remote termination of Fast-DDS. If the fields of `PID_IDENTITY_TOKEN` or `PID_PERMISSIONS_TOKEN` in the DATA Submessage are tampered with — specially `readOctetVector` reads an unchecked `vecsize` that is propagated unchanged into `readData` as the `length` parameter — the attacker-contro lled `vecsize` can trigger a 32-bit integer overflow during the `length` calculation. That overflow can cause large alloca tion attempt that quickly leads to OOM, enabling a remotely-triggerable denial-of-service and remote process termination. Versions 3.4.1, 3.3.1, and 2.6.11 patch the issue.