# CVE-2024-1023: Io.vertx/vertx-core: memory leak due to the use of netty fastthreadlocal data structures in vertx

> Attackers can cause memory leaks in Vert.x HTTP clients by connecting to arbitrary hosts, leading to denial of service.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Mar 2024
- **Updated:** 23 Sep 2026
- **Also known as:** GHSA-5667-3wch-7q7w

## What is CVE-2024-1023?

CVE-2024-1023 is a medium-severity denial of service vulnerability in Red Hat A-MQ Clients 2, published on 27 Mar 2024. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the Eclipse Vert.x toolkit results in a memory leak due to using Netty FastThreadLocal data structures. Specifically, when the Vert.x HTTP client establishes connections to different hosts, triggering the memory leak. The leak can be accelerated with intimate runtime knowledge, allowing an attacker to exploit this vulnerability. For instance, a server accepting arbitrary internet addresses could serve as an attack vector by connecting to these addresses, thereby accelerating the memory leak.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2024-1023?

4 open source packages ship an affected version, including io.vertx:vertx-core.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `io.vertx:vertx-core` | Maven | From 4.4.5 | 4.4.7 |
| `io.vertx:vertx-core` | Maven | From 4.4.5 | 4.4.7 |
| `io.vertx:vertx-core` | Maven | From 4.5.0 | 4.5.2 |
| `io.vertx:vertx-core` | Maven | From 4.5.0 | 4.5.2 |

## How do I fix CVE-2024-1023?

Upgrade io.vertx:vertx-core to a fixed version for your release line: 4.4.7 or 4.5.2.

## Is CVE-2024-1023 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-1023 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-1023 and fix it if it is affected.

What it is: CVE-2024-1023 is a medium-severity denial of service vulnerability in Red Hat A-MQ Clients 2, published on 27 Mar 2024. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-1023 exists.

Affected packages and fixed versions:
- io.vertx:vertx-core (Maven): affected from 4.4.5; fixed in 4.4.7
- io.vertx:vertx-core (Maven): affected from 4.4.5; fixed in 4.4.7
- io.vertx:vertx-core (Maven): affected from 4.5.0; fixed in 4.5.2
- io.vertx:vertx-core (Maven): affected from 4.5.0; fixed in 4.5.2

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-2024-1023/ (Markdown: https://insights.sbomify.com/CVE-2024-1023/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-1023
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-1023
- OSV: https://osv.dev/vulnerability/CVE-2024-1023

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-1023/
Summaries are generated and may contain mistakes; the official description above is the record.