CVE-2026-33558: Apache Kafka, Apache Kafka Clients: Information Exposure Through Network Client Log Output
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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33558?
CVE-2026-33558 has been assigned a moderate severity level due to potential information exposure risks.
How do I fix CVE-2026-33558?
To mitigate CVE-2026-33558, disable DEBUG logging or configure logging levels appropriately to avoid exposing sensitive information.
Which versions of Apache Kafka are affected by CVE-2026-33558?
CVE-2026-33558 affects Apache Kafka versions 3.9.1 and earlier, as well as 4.0.0 and earlier.
What type of information can be exposed by CVE-2026-33558?
CVE-2026-33558 can expose entire requests and responses logged at the DEBUG level, including potentially sensitive data.
Is this vulnerability applicable to Apache Kafka Clients as well?
Yes, CVE-2026-33558 also impacts Apache Kafka Clients versions 3.9.1 and earlier, as well as 4.0.0 and earlier.