CVE-2026-33558: Information exposure vulnerability has been identified in Apache Kafka. The NetworkClient component will output entire requests and responses informa...

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.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS Probability

0.53%

41.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-533

Affected Software

Vendor	Product	Versions
Apache	Kafka	>= 0.11.0.0, < 3.9.2
Apache	Kafka	4.0.0

References

https://kafka.apache.org/cve-listVendor Advisory
https://lists.apache.org/thread/pz5g4ky3h0k91tfd14p0dzqjp80960klMitigation, Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/04/17/3Mailing List

Timeline

Published: Apr 20, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-33558?

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.

How severe is CVE-2026-33558?

CVE-2026-33558 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.53% probability of exploitation in the next 30 days.

How do I fix CVE-2026-33558?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.