# CVE-2026-102464: Denial of service in Eclipse Vert.x

> A malicious MQTT broker can cause unbounded memory growth in Vert.x MQTT clients by withholding PUBREL packets, leading to denial of service.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-46xj-5735-6qrp, GHSA-g3vx-j9rx-jfm5

## What is CVE-2026-102464?

CVE-2026-102464 is a high-severity denial of service vulnerability in Eclipse Vert.x, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In Eclipse Vert.x versions [4.0.0, 4.5.34] or [5.0.0,5.0.12] or [5.1.0,5.1.9] or [5.2.0, 5.2.0], the Eclipse Vert.x MQTT (vertx-mqtt) MqttClient stores every inbound QoS 2 PUBLISH message received from the broker in an internal map (qos2inbound) while awaiting the corresponding PUBREL packet to complete the QoS 2 handshake. This map has no size limit; the maxInflightQueue option is enforced only on the outbound publish path and does not constrain inbound message retention.

A malicious or compromised MQTT broker can exploit this by sending QoS 2 PUBLISH messages with distinct packet identifiers and withholding the PUBREL responses. Each incomplete handshake causes the client to retain the full publish message (topic, payload, and metadata) indefinitely, leading to unbounded memory growth in the Vert.x process. This can degrade the MQTT-consuming application or cause out-of-memory termination.

The impacted component is io.vertx:vertx-mqtt.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-102464?

It affects 1 product.


Products: Eclipse Vert.x.

## How do I fix CVE-2026-102464?

No fix has been published for CVE-2026-102464 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-102464 being exploited?

There is no known exploitation of CVE-2026-102464 in the wild and no public exploit code.

## Other vulnerabilities in Eclipse Vert.x

- [CVE-2019-17640](https://insights.sbomify.com/CVE-2019-17640/): Path Traversal in Eclipse Vert (critical 9.8)
- [CVE-2018-12542](https://insights.sbomify.com/CVE-2018-12542/): Eclipse Vert.x does not properly neutralize '' (forward slashes) sequences that can resolve to an external location (critical 9.8)
- [CVE-2018-12544](https://insights.sbomify.com/CVE-2018-12544/): Moderate severity vulnerability that affects io.vertx:vertx-core (critical 9.8)
- [CVE-2026-102469](https://insights.sbomify.com/CVE-2026-102469/): Deserialization in Eclipse Vert.x (critical 9.2)
- [CVE-2018-12540](https://insights.sbomify.com/CVE-2018-12540/): High severity vulnerability that affects io.vertx:vertx-web (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102464 and fix it if it is affected.

What it is: CVE-2026-102464 is a high-severity denial of service vulnerability in Eclipse Vert.x, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-102464 in the wild and no public exploit code.

Affected product: Eclipse Vert.x. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-102464/ (Markdown: https://insights.sbomify.com/CVE-2026-102464/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102464
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102464
- OSV: https://osv.dev/vulnerability/CVE-2026-102464

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102464/
Summaries are generated and may contain mistakes; the official description above is the record.