CVE-2025-62723
MediumCVSS 4.3Exploitation Probability (EPSS)
Low risk25th percentile - higher than 25% of all known CVEs
Summary
FlashMQ is a MQTT broker/server, designed for multi-CPU environments. Prior to version 1.23.2, any authenticated user can create sessions and have them collect QoS messages. When not sent to a client, these are then not released upon (eventual) session expiration. Version 1.23.2 fixes the issue.
Risk Assessment
An attacker could intentionally create sessions and accumulate messages, potentially exhausting memory or other resources, causing broker unavailability.
Recommendation
Update FlashMQ to version 1.23.2 or later, which includes the fix, and monitor resource usage.
Other vulnerabilities in FlashMQ
See all- CVE-2026-46411Medium
FlashMQ before version 1.26.2 allows authorized clients to exceed the permitted over-commit of their write buffer, triggering an internal safe-guard exception. This exception is in a path that cannot be caught, causing a server abort.
- CVE-2026-42209Medium
In FlashMQ prior to version 1.26.1, a remote client with retained publish permission can crash the 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. The issue is patched in version 1.26.1.
Original NVD description (English source)
FlashMQ is a MQTT broker/server, designed for multi-CPU environments. Prior to version 1.23.2, any authenticated user can create sessions and have them collect QoS messages. When not sent to a client, these are then not released upon (eventual) session expiration. Version 1.23.2 fixes the issue.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS