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.

A flaw was found in the Apache Pulsar Java Client. This flaw allows an attacker to use a Man-in-the-Middle (MITM) attack, manipulating network traffic and gaining the client's authentication data.

Improper Input Validation vulnerability in Proxy component of Apache Pulsar allows an attacker to make TCP/IP connection attempts that originate from the Pulsar Proxy's IP address. When the Apache Pulsar Proxy component is used, it is possible to attempt to open TCP/IP connections to any IP address and port that the Pulsar Proxy can connect to. An attacker could use this as a way for DoS attacks that originate from the Pulsar Proxy's IP address. It hasn’t been detected that the Pulsar Proxy authentication can be bypassed. The attacker will have to have a valid token to a properly secured Pulsar Proxy. This issue affects Apache Pulsar Proxy versions 2.7.0 to 2.7.4; 2.8.0 to 2.8.2; 2.9.0 to 2.9.1; 2.6.4 and earlier.

Apache Pulsar Brokers and Proxies create an internal Pulsar Admin Client that does not verify peer TLS certificates, even when tlsAllowInsecureConnection is disabled via configuration. The Pulsar Admin Client's intra-cluster and geo-replication HTTPS connections are vulnerable to man in the middle attacks, which could leak authentication data, configuration data, and any other data sent by these clients. 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. This issue affects Apache Pulsar Broker and 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.