# CVE-2026-63336: RabbitMQ Java client: TrustEverythingTrustManager used by default in useSslProtocol() enables MITM

> A network attacker can perform man-in-the-middle attacks on RabbitMQ connections because the Java client library defaults to accepting any TLS certificate without hostname verification.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N`)
- **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:** 18 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** CLEANSTART-2026-WB40347, CLSA-2026-1791800237, DEBIAN-CVE-2026-63336, ECHO-e155-bf0d-659d, GHSA-5m9f-rphj-c435, MINI-26m6-pjvc-m3xq, MINI-2fvw-98hc-qvfv, MINI-2rc4-rcp9-269h, MINI-2w6m-9j7r-fff7, MINI-53f6-6p83-j7vp, MINI-74xx-rr8r-7w2h, MINI-7hp5-x33m-rmvv, MINI-9458-94wq-3hpg, MINI-frwm-7hh8-vxcm, MINI-mcpx-7865-q2g2, MINI-p6xx-6qq6-8p58, MINI-prwp-pv75-h3ww, MINI-vcx5-5x67-f73c, MINI-vrqc-6gv7-g43c, MINI-wwc6-c3fh-cqrf, UBUNTU-CVE-2026-63336

## What is CVE-2026-63336?

CVE-2026-63336 is a medium-severity vulnerability in rabbitmq-java-client, published on 18 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes. Prior to 5.33.0, com.rabbitmq.client.ConnectionFactory.useSslProtocol() and ConnectionFactory.useSslProtocol(String) configure com.rabbitmq.client.TrustEverythingTrustManager and leave hostname verification disabled, causing arbitrary server certificates, including self-signed certificates, to be accepted. A network attacker able to intercept a TLS connection can impersonate the RabbitMQ broker, read protected AMQP traffic, and modify traffic without certificate or hostname validation. The fix changes the production TLS helpers to use the JVM default trust store and enables hostname verification, while retaining an explicitly named development-only no-verification helper. This issue is fixed in version 5.33.0.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-63336?

2 open source packages ship an affected version, including com.rabbitmq:amqp-client.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.rabbitmq:amqp-client` | Maven | All versions | 5.33.0 |
| `com.rabbitmq:amqp-client` | Maven | All versions | 5.33.0 |

## How do I fix CVE-2026-63336?

Upgrade com.rabbitmq:amqp-client to 5.33.0 or later.

## Is CVE-2026-63336 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63336 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63336 and fix it if it is affected.

What it is: CVE-2026-63336 is a medium-severity vulnerability in rabbitmq-java-client, published on 18 Aug 2026. 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-2026-63336 exists.

Affected packages and fixed versions:
- com.rabbitmq:amqp-client (Maven): affected all versions; fixed in 5.33.0
- com.rabbitmq:amqp-client (Maven): affected all versions; fixed in 5.33.0

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-2026-63336/ (Markdown: https://insights.sbomify.com/CVE-2026-63336/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63336
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63336
- OSV: https://osv.dev/vulnerability/CVE-2026-63336

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63336/
Summaries are generated and may contain mistakes; the official description above is the record.