CVE-2026-33558

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

State: Published
Severity: 5.3 Medium
Published: Apr 20, 2026
Updated: Apr 20, 2026
Reserved: Mar 23, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	5.3 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N	CISA-ADP

Weaknesses

CWE-533 DEPRECATED: Information Exposure Through Server Log Files

Affected Products

Product	Versions
Apache KafkaApache Software Foundation	0.11.0 through 3.9.1Affected 4.0.0Affected
Apache Kafka ClientsApache Software Foundation	0.11.0 through 3.9.1Affected 4.0.0Affected

References

https://kafka.apache.org/cve-listvendor-advisory
https://lists.apache.org/thread/pz5g4ky3h0k91tfd14p0dzqjp80960klmailing-list
http://www.openwall.com/lists/oss-security/2026/04/17/3

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