CVE-2022-33684: Apache Pulsar: Disabled Certificate Validation for OAuth Client Credential Requests makes C++/Python Clients vulnerable to MITM attack

[Michael Marshall <mmarshall () apache org>]

Severity: high

Description:

The Apache Pulsar C++ Client does not verify peer TLS certificates when making HTTPS calls for the OAuth2.0 Client 
Credential Flow, even when tlsAllowInsecureConnection is disabled via configuration. This vulnerability allows an 
attacker to perform a man in the middle attack and intercept and/or modify the GET request that is sent to the 
ClientCredentialFlow 'issuer url'. The intercepted credentials can be used to acquire authentication data from the 
OAuth2.0 server to then authenticate with an Apache Pulsar cluster.

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.

The Apache Pulsar Python Client wraps the C++ client, so it is also vulnerable in the same way.

This issue affects Apache Pulsar C++ Client and Python Client 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 to 2.10.1; 2.6.4 and earlier.

Mitigation:

Any users running affected versions of the C++ Client or the Python Client should rotate vulnerable OAuth2.0 
credentials, including client_id and client_secret.

2.7 C++ and Python Client users should upgrade to 2.7.5 and rotate vulnerable OAuth2.0 credentials.
2.8 C++ and Python Client users should upgrade to 2.8.4 and rotate vulnerable OAuth2.0 credentials.
2.9 C++ and Python Client users should upgrade to 2.9.3 and rotate vulnerable OAuth2.0 credentials.
2.10 C++ and Python Client users should upgrade to 2.10.2 and rotate vulnerable OAuth2.0 credentials.
3.0 C++ users are unaffected and 3.0 Python Client users will be unaffected when it is released.
Any users running the C++ and Python Client for 2.6 or less should upgrade to one of the above patched versions.

Credit:

This issue was discovered by Michael Rowley, michaellrowley () protonmail com