CVE-2026-42209 | THREATINT

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.

PUBLISHED Reserved 2026-04-25 | Published 2026-05-08 | Updated 2026-05-08 | Assigner GitHub_M

MEDIUM: 6.5CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-369: Divide By Zero

Product status

< 1.26.1

affected

References

github.com/...lashMQ/security/advisories/GHSA-2789-vfcg-5922

github.com/halfgaar/FlashMQ/issues/167

github.com/...ommit/193b6e7767889511cfa8e933908ea5e6a1077a1f

github.com/halfgaar/FlashMQ/releases/tag/v1.26.1

cve.org (CVE-2026-42209)

nvd.nist.gov (CVE-2026-42209)

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