CVE-2026-42209
FlashMQ: Division by zero crash when using non-default deferred retained message setting
- State
- Published
- Severity
- 6.5 Medium
- Published
- May 8, 2026
- Updated
- May 11, 2026
- Reserved
- Apr 25, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.5 Medium | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
Weaknesses
- CWE-369 Divide By Zero
Affected Products
| Product | Versions |
|---|---|
FlashMQhalfgaar |
|
References
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