CVE-2026-33558 PUBLISHED

Apache Kafka, Apache Kafka Clients: Information Exposure Through Network Client Log Output

Assigner: apache
Reserved: 23.03.2026 Published: 20.04.2026 Updated: 20.04.2026

Information exposure vulnerability has been identified in Apache Kafka.

The NetworkClient component will output entire requests and responses information in the DEBUG log level in the logs. By default, the log level is set to INFO level. If the DEBUG level is enabled, the sensitive information will be exposed via the requests and responses output log. The entire lists of impacted requests and responses are:

  • AlterConfigsRequest

  • AlterUserScramCredentialsRequest

  • ExpireDelegationTokenRequest

  • IncrementalAlterConfigsRequest

  • RenewDelegationTokenRequest

  • SaslAuthenticateRequest

  • createDelegationTokenResponse

  • describeDelegationTokenResponse

  • SaslAuthenticateResponse

This issue affects Apache Kafka: from any version supported the listed API above through v3.9.1, v4.0.0. We advise the Kafka users to upgrade to v3.9.2, v4.0.1, or later to avoid this vulnerability.

Product Status

Vendor Apache Software Foundation
Product Apache Kafka
Versions Default: unaffected
  • affected from 0.11.0 to 3.9.1 (incl.)
  • Version 4.0.0 is affected
Vendor Apache Software Foundation
Product Apache Kafka Clients
Versions Default: unaffected
  • affected from 0.11.0 to 3.9.1 (incl.)
  • Version 4.0.0 is affected

Credits

  • Alyssa Huang <ahuang@confluent.io> finder
  • Luke Chen <showuon@gmail.com> finder

References

Problem Types

  • CWE-533 DEPRECATED: Information Exposure Through Server Log Files CWE