{"id":"CVE-2026-42209","state":"PUBLISHED","title":"FlashMQ: Division by zero crash when using non-default deferred retained message setting","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.","publishedAt":"2026-05-08T21:40:43.284Z","updatedAt":"2026-05-11T15:59:27.626Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["halfgaar FlashMQ"],"affected":[{"vendor":"halfgaar","product":"FlashMQ","versions":[{"version":"< 1.26.1","status":"affected"}]}],"references":["https://github.com/halfgaar/FlashMQ/security/advisories/GHSA-2789-vfcg-5922","https://github.com/halfgaar/FlashMQ/issues/167","https://github.com/halfgaar/FlashMQ/commit/193b6e7767889511cfa8e933908ea5e6a1077a1f","https://github.com/halfgaar/FlashMQ/releases/tag/v1.26.1"],"weaknesses":["CWE-369"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/42xxx/CVE-2026-42209.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-42209","state":"PUBLISHED","datePublished":"2026-05-08T21:40:43.284Z","dateUpdated":"2026-05-11T15:59:27.626Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-04-25T05:04:37.028Z"},"containers":{"cna":{"title":"FlashMQ: Division by zero crash when using non-default deferred retained message setting","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"halfgaar","product":"FlashMQ","versions":[{"version":"< 1.26.1","status":"affected"}]}],"references":[{"url":"https://github.com/halfgaar/FlashMQ/security/advisories/GHSA-2789-vfcg-5922","name":"https://github.com/halfgaar/FlashMQ/security/advisories/GHSA-2789-vfcg-5922","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/halfgaar/FlashMQ/issues/167","name":"https://github.com/halfgaar/FlashMQ/issues/167","tags":["x_refsource_MISC"]},{"url":"https://github.com/halfgaar/FlashMQ/commit/193b6e7767889511cfa8e933908ea5e6a1077a1f","name":"https://github.com/halfgaar/FlashMQ/commit/193b6e7767889511cfa8e933908ea5e6a1077a1f","tags":["x_refsource_MISC"]},{"url":"https://github.com/halfgaar/FlashMQ/releases/tag/v1.26.1","name":"https://github.com/halfgaar/FlashMQ/releases/tag/v1.26.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-369","lang":"en","description":"CWE-369: Divide By Zero","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-08T21:40:43.284Z"},"source":{"advisory":"GHSA-2789-vfcg-5922","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/halfgaar/FlashMQ/issues/167","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-11T15:59:23.887272Z","id":"CVE-2026-42209","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-11T15:59:27.626Z"}}]}}}