The Common Vulnerabilities and Exposures (CVE) system has recently issued an advisory with the identifier CVE-2023-29471 [1]. Lightbend's Alpakka Kafka library, prior to its version 5.., contains a vulnerability that causes user credentials to be logged as debugging information. This issue exists in the akka.kafka.internal.KafkaConsumerActor class, and it specifically affects configurations with plaintext login details. In this post, we'll explore the details of this security flaw, its implications, and recommended mitigations.

Original References

1. CVE:
2. Lightbend Alpakka Kafka:

Code Snippet

The flaw lies within the akka.kafka.internal.KafkaConsumerActor class; specifically, the preStart() method. Here's an excerpt:

override def preStart(): Unit = {
  log.debug("Starting Kafka consumer {}", settings)

As seen in this snippet, the settings object is logged as debug information. Unfortunately, this object can contain user login credentials when the plain cleartext login is configured. Consequently, this can lead to sensitive data being leaked via log files.

The leaking of credentials in log files poses several risks

1. Unauthorized access: Malicious actors could exploit the leaked credentials to gain unauthorized access to the Kafka broker.
2. Information disclosure: The attained credentials may provide attackers with information on other connected systems, paving the way for additional breaches.
3. Log file exposure: Log files are often stored or backed up in multiple locations, making it increasingly difficult to identify and eliminate all instances of the leaked data.


Given the significance of this security issue, it is critical to address it promptly. Users of the Alpakka Kafka library must take the following steps:

1. Upgrade: First, upgrade to the latest version of the Alpakka Kafka library – specifically, version 5.. or later. This version provides a fix for the credential leakage vulnerability.
2. Remove log files: Locate and remove any log files containing sensitive data. Be sure to check backups and secondary storage systems.
3. Update credentials: As an additional precaution, it's recommended to update the affected user credentials to prevent unauthorized access.


The CVE-2023-29471 highlights the need for proper security practices in software development, as well as the potential risks of seemingly harmless debugging practices. Upgrading to the latest version of the library and following recommended steps to clean the log files and update the credentials will help to secure your application against this vulnerability.

Remember that keeping your libraries up-to-date and monitoring for security advisories is a vital aspect of responsible software development. Stay ahead of potential issues, and ensure that your applications remain secure.

For additional information, consult the official Github repository for Lightbend Alpakka Kafka [2], and find the full details on the CVE page [1].


Published on: 04/27/2023 21:15:00 UTC
Last modified on: 05/05/2023 18:11:00 UTC