Flashmq CVEs and Security Vulnerabilities

CVE-2026-46411

FlashMQ: Client can trigger uncaught exception on FlashMQ 1.26.1 and older

FlashMQ is a MQTT broker/server, designed for multi-CPU environments. Prior to version 1.26.2, authorized clients have the ability to exceed the permitted over-commit of their write buffer and triggering an internal safe-guard exception. This exception was in a path that was not catchable, and therefore causes a server abort. This issue has been patched in version 1.26.2.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Halfgaar

Products

Flashmq

CVE-2026-42209

FlashMQ: Division by zero crash when using non-default deferred retained message setting

FlashMQ is a MQTT broker/server, designed for multi-CPU environments. Prior to version 1.26.1, a remote client with retained publish permission can crash the FlashMQ broker when both set_retained_message_defer_timeout and set_retained_message_defer_timeout_spread are configured to non-default values, resulting in denial of service. If anonymous retained publishing is allowed, no authentication is required; otherwise, the attacker needs the corresponding publish permission. This issue has been patched in version 1.26.1.