NATS v2.14.4

This maintenance release focuses heavily on the stability and performance of JetStream, addressing several race conditions in the filestore and optimizing memory usage during message deletion and snapshotting. It also includes critical security hardening for authentication bypass scenarios and significant reliability fixes for MQTT and Raft-based clustering.

Critical Authentication and Permission Fixes — Prevents unauthorized access in specific TLS and authentication configurations, ensuring that security policies are strictly enforced even when users omit certain connection parameters.

JetStream Storage and IO Optimizations — High-volume JetStream users, particularly those with frequent message deletions, will see lower latency and reduced CPU/memory overhead during disk operations and snapshotting.

Improved Raft Consensus and Clustering Stability — Increases the robustness of NATS clusters by preventing stale leader proposals and ensuring that nodes returning from downtime correctly synchronize with the current stream state.

Enhanced MQTT Protocol Compliance and Reliability — Reliability improvements for MQTT workloads, ensuring message identifiers are unique and Quality of Service (QoS) levels are maintained correctly during session resumes.

Configurable JetStream Disk Concurrency — Operators can now fine-tune disk I/O performance via the max_concurrent_io setting, allowing for better resource management on various storage backends.