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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
Which versions are affected by CVE-2026-63336?
2 open source packages ship an affected version, including com.rabbitmq:amqp-client.
| Package | 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.
Sources
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 and 15 more.