Respond.io vs Rspamd

Rspamd's 4.1.x line is running two tracks at once: extending the neural and fuzzy subsystems it rebuilt earlier in the cycle, and auditing its own attack surface. 4.1.5 continues both — fuzzy storages now receive sender authentication facts over encrypted rules, the PDF parser decodes text through font encodings and ToUnicode CMaps, and the protocol gates File, Path and Shm message sources that any TCP client could previously use to have arbitrary files parsed. That gate ships as an opt-out now and an opt-in later.

Every release in this window has carried at least one security fix in the same class: a controller accepting any password on a malformed hash, a DKIM out-of-bounds read, MIME recursion depth, and now unauthenticated file reads. The project is systematically walking its own input paths rather than reacting to individual reports. Alongside it, the fuzzy subsystem keeps gaining structure — diagnostics, persisted shingle sets, and now shared sender reputation signals — turning what was a hash-match check into a scored, introspectable component.

The stated plan to flip allow_file_and_shm_inputs to false in the next major release makes that the visible breaking change to prepare for. Expect the fuzzy work to keep consolidating, since sharing SPF, DKIM and DMARC state with storages sets up cross-sender scoring that the current per-hash matching cannot express.