CVE-2026-42209 — MEDIUM (6.5)

Vulnerability Description

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.

CVSS Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

NONE

Integrity

NONE

Availability

HIGH

Related Weaknesses (CWE)

CWE-369

References

FAQ

What is CVE-2026-42209?

CVE-2026-42209 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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_mess...

How severe is CVE-2026-42209?

CVE-2026-42209 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-42209?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.