CVE-2026-63341: DoS (CVSS 7.5)

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.

Is your site exposed to CVE-2026-63341?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-248 CWE-248

CWE-400 Uncontrolled Resource Consumption

References

Other References

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

Frequently Asked Questions

What is CVE-2026-63341? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-63341? +

CVE-2026-63341 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2026-63341? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-24883

go-ethereum (geth) is a golang execution layer implementation of the Ethereum protocol. A vulnerable node can be forced to shutdown/crash …

CVE-2025-43855

tRPC allows users to build & consume fully typesafe APIs without schemas or code generation. In versions starting from 11.0.0 …

CVE-2025-48997

Multer is a node.js middleware for handling `multipart/form-data`. A vulnerability that is present starting in version 1.4.4-lts.1 and prior to …

CVE-2025-53365

The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to …

CVE-2025-53366

The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to …

CVE-2025-53620

@builder.io/qwik-city is the meta-framework for Qwik. When a Qwik Server Action QRL is executed it dynamically load the file containing …

CVE-2026-63341