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PYSEC-2026-901
No affected components available
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.
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.
The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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