wolfMQTT v2.0.0 (20MAR2026)

v2.0.0 (03/20/2026)

Release 2.0.0 has been developed according to wolfSSL's development and QA
process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

• New Features

  • Lightweight MQTT Broker — New built-in MQTT broker implementation (#457)
  • MQTT v3.1.1 spec compliance checks (#462)
  • Secure and non-secure port listening support (#465)
  • WebSocket transport support (#466)
  • wolfIP (embedded TCP/IP stack) support (#463)
  • Retained messages, session persistence, graceful disconnect, QoS subscription updates (#465)
  • libFuzzer-based broker fuzzing infrastructure (#474)
  • wolfIP Integration — Added wolfIP support for both MQTT client and broker (#463)
  • lastError Field — Preserve TLS error code via new lastError in the network context (#458)

• Bug Fixes

  • Fix race condition in wm_SemLock (#475)
  • Fix wildcard topic matching (#472)
  • Fix LWT (Last Will and Testament) length checks and payload free issues (#472, #473)
  • Fix subAck buffer size check and topic count validation (#472)
  • Fix MqttPacket_Write failure return handling (#473)
  • Fix MQTT-SN: null pointer dereference, non-blocking read, encode/decode issues (#473)
  • Fix MqttDecode_Auth reason code issue (#473)
  • Fix broker client connect status check (#472)
  • Fix SN_Client_WaitType issues (#456)
  • Fix curl transport: use internal loops for partial read/write handling (#459)

• Security Hardening

  • Add overflow checks in network and socket IO (#467)
  • Add checks for negative return values in MqttDecode_String calls (#467)
  • Add encoding error checks (#467)
  • Add remain_len validation check (#471)
  • Static analysis fixes for MqttClient_Auth, MqttProps_Add, MqttDecode_SubscribeAck, MqttDecode_Props (#469)
  • Static analysis fixes for SN_Decode_Register, SN_Decode_GWInfo, SN_Client_WillTopicUpdate, SN_Encode_Publish, SN_Encode_RegAck, SN_Client_Connect (#468)
  • Add debug warning when using VERIFY_NONE (#475)

• CI / Testing

  • Add CI workflows for codespell, multi-compiler, and sanitizer tests (#470)
  • Add Coverity workflow schedule (#450, #451)
  • Add WebSocket broker configurations to CI (#466)
  • Expanded broker edge case testing (#465)
  • Improved broker test execution speed (#465)

• Other

  • Updated client certificates (#455)
  • Added wolfSSL as submodule option (#452)

wolfMQTT v1.21.0 (03DEC2025)

Release 1.21.0 has been developed according to wolfSSL's development and QA
process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

What's Changed

• Add port for NETX use by @JacobBarthelmeh in #427
• Fix heap buffer overflow in MqttDecode_Num with bounds checking by @devin-ai-integration[bot] in #430
• Restore instructions for testing against OQS mosquitto integration. by @anhu in #432
• initial threadx test by @JacobBarthelmeh in #429
• Rename ML-KEM hybrids to match IETF Draft. by @anhu in #435
• Update expired test certs by @lealem47 in #441
• Pin to ESP-IDF v5.5, limit workflow push branches, line endings by @gojimmypi in #444
• Fix: MQTT v5 Property-Packet Protocol Validation and Decode Safety by @kaabia in #440
• Fix: Correct state transition check in MqttClient_Auth by @kaabia in #439
• fix: correct variable in MQTT property decode error checks by @kaabia in #445
• Add fflush to mqtt-sub example by @embhorn in #447
• Update license to GPLv3 by @embhorn in #448

wolfMQTT v1.20.0 (02MAY2025)

v1.20.0 (05/02/2025)

Release 1.20.0 has been developed according to wolfSSL's development and QA
process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

• OQS's Mosquitto is out of date. by @anhu in #417
• Add support for websocket by @embhorn in #418
• Add support for secure websockets by @embhorn in #419
• Add secure ws CI test by @embhorn in #421
• Update examples for latest Managed Components by @gojimmypi in #420
• Improve cmake duplicate component check by @gojimmypi in #422

wolfMQTT v1.19.2 (31JAN2025)

v1.19.2 (01/31/2025)

Release 1.19.2 has been developed according to wolfSSL's development and QA
process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

• Handle connection error in mqttsimple client by @embhorn in #407
• Fix stat reset for ping response by @embhorn in #414

wolfMQTT v1.19.1 (06NOV2024)

v1.19.1 (11/06/2024)

Release 1.19.1 has been developed according to wolfSSL's development and QA process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

• wolfssl 5.7.2 time_helper type adjustments for Espressif example by @gojimmypi in #404
• Fix Doxygen issues by @embhorn in #403

wolfMQTT v1.19.0 (22MAR2024)

v1.19.0 (3/22/2024)
Release 1.19.0 has been developed according to wolfSSL's development and QA process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

• Add stress test. by @philljj in #387
• Add cmake CI test and fix pthread detection by @embhorn in #389
• Initial wolfMQTT Espressif ESP32 template and AWS IoT examples by @gojimmypi in #388
• Add curl test dependencies by @lealem47 in #392
• Improving and fixing typos for STM32CUBE build by @lealem47 in #391
• Fix string prop OOB read by @embhorn in #394
• Fix some Helgrind thread errors with enable-tls, and enable-curl. by @philljj in #396
• Initial Espressif CI; limit Zepher CI by @gojimmypi in #390
• Fix double unlock and double lock in multithread example. by @philljj in #397
• Fix double lock of lockRecv. by @philljj in #398

wolfMQTT v1.18.0 (22DEC2023)

v1.18.0 (12/22/2023)

Release 1.18.0 has been developed according to wolfSSL's development and QA process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

• Add curl easy socket backend. by @philljj in #380
• WOLFMQTT_EXAMPLE_CERT allowing static or extern cert assignment by @gojimmypi in #354
• Tiny readme cleanup. by @philljj in #381
• Fix high coverity issues by @embhorn in #379
• Add broker check to scripts by @embhorn in #385
• Cmake build fixes by @embhorn in #384

wolfMQTT v1.17.1 (29NOV2023)

v1.17.1 (11/29/2023)

Release 1.17.1 has been developed according to wolfSSL's development and QA process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

• Include stdint.h in userio_template.h by @lealem47 in #371
• Improvements to multithread locking and tests. by @dgarske in #369
• Cleanup executable status on src files. by @philljj in #372
• Close socket on error in NetConnect by @embhorn in #375
• Fixes for non-blocking with larger payload and improvements to the test and examples by @dgarske in #373
• Add MQTT-SN CI tests by @embhorn in #376
• Fix Wild read in MqttProps_Free by @embhorn in #377
• Fix fuzzer issues in MqttDecode_Props by @embhorn in #378

wolfMQTT v1.17.0 (02NOV2023)

v1.17.0 (11/2/2023)

Release 1.17.0 has been developed according to wolfSSL's development and QA process (see link below) and successfully passed the quality criteria.
https://www.wolfssl.com/about/wolfssl-software-development-process-quality-assurance

• Fix for declaration after executable block by @lealem47 in #341
• Add QNX IDE, Makefile, and remove source code exec bit by @JacobBarthelmeh
  in #317
• update for cmake after wolfssl added NAMESPACE by @JacobBarthelmeh in #343
• Add mutex protection to MqttClient_NetDisconnect by @embhorn in #342
• Add DTLS support to MQTT-SN client by @embhorn in #348
• Tie zephyr tests to a release by @julek-wolfssl in #350
• add documentation link to README by @gojimmypi in #355
• Possible patch for POSIX conditional wait issue by @dgarske in #356
• Fix publish with topic ID >=127 by @embhorn in #351
• Adding publish and subscribe atomic client examples by @embhorn in #347
• Allow disabling the posix conditional signal by @dgarske in #360
• Exclude CI tests with external brokers by @embhorn in #362
• Improvements for client property stack by @dgarske in #361
• Add mosquitto to CI tests by @embhorn in #365
• Fixes for non-blocking edge cases by @dgarske in #363
• Refactor MQTT-SN code by @embhorn in #366

wolfMQTT v1.16.0 (29JUN2023)

v1.16.0 (6/29/2023)

• Add testing for TLS mutual auth, and fsanitize gh test by @lealem47 in #321
• Add support for pkcs8 keys to mqtt client by @lealem47 in #322
• Fix null ptr deref in MqttClient_WaitType by @embhorn in #323
• Cleanup enum last entry to not have comma by @dgarske in #324
• Cleanup the AWS example by @dgarske in #326
• Fix for multi-threaded non-blocking use of sockRc, which could collide between read and write by @dgarske in #328
• Add API to check if message is active (non-blocking only) by @dgarske in #329
• Fix configure warnings by @embhorn in #330
• Support MQTTv5 in AWS example by @embhorn in #332
• Zephyr port by @julek-wolfssl in #333
• Improve example headers and small sanitizer fixes by @lealem47 in #334
• Adding in STM32CubeIDE support by @lealem47 in #335
• Add dynamic property support by @embhorn in #336