CVE-2026-42209CWE-369

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

Medium · published May 8, 2026

CVSS v3.1
6.5
EPSS
1%
Percentile
50.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00646 · 50.3th percentile
Weakness
CWE-369 · Divide By Zero
Published
2026-05-08T21:40Z
EPSS history
Timeline
  • 08 MAY 21:40Z
    FlashMQ: Division by zero crash when using non-default deferred retained message setting
    cvelistv5