Disabled Hostname Verification makes Brokers, Proxies vulnerable to MITM attack

Summary

TLS hostname verification cannot be enabled in the Pulsar Broker's Java Client, the Pulsar Broker's Java Admin Client, the Pulsar WebSocket Proxy's Java Client, and the Pulsar Proxy's Admin Client leaving intra-cluster connections and geo-replication connections vulnerable to man in the middle attacks, which could leak credentials, configuration data, message data, and any other data sent by these clients. The vulnerability is for both the pulsar+ssl protocol and HTTPS. An attacker can only take advantage of this vulnerability by taking control of a machine 'between' the client and the server. The attacker must then actively manipulate traffic to perform the attack by providing the client with a cryptographically valid certificate for an unrelated host. This issue affects Apache Pulsar Broker, Proxy, and WebSocket Proxy versions 2.7.0 to 2.7.4; 2.8.0 to 2.8.3; 2.9.0 to 2.9.2; 2.10.0; 2.6.4 and earlier.

Timeline

1. Sep 23, 2022, 9:25 AM UTCCVE published
2. May 27, 2025, 2:45 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. May 27, 2025, 2:46 PM UTCRecord last updated

Affected versions

• Apache Software Foundation Apache Pulsar

  From 2.7 · through 2.7.4; From 2.8 · through 2.8.3; From 2.9 · through 2.9.2; through 2.6.4

• org.apache.pulsar:pulsar-brokerMaven

  fixed in 2.7.5

• org.apache.pulsar:pulsar-proxyMaven

  fixed in 2.7.5

• org.apache.pulsar:pulsar-brokerMaven

  From 2.8.0 · fixed in 2.8.4

• org.apache.pulsar:pulsar-proxyMaven

  From 2.8.0 · fixed in 2.8.4

• org.apache.pulsar:pulsar-brokerMaven

  From 2.9.0 · fixed in 2.9.3

• org.apache.pulsar:pulsar-proxyMaven

  From 2.9.0 · fixed in 2.9.3

• org.apache.pulsar:pulsar-brokerMaven

  From 2.10.0 · fixed in 2.10.1

• org.apache.pulsar:pulsar-proxyMaven

  From 2.10.0 · fixed in 2.10.1

References 1