Medium5.3Apache Software Foundation

Medium [CVE-2026-33558] Apache Kafka: Information exposure vulnerability has been identified in Apache Kafka.

This medium-severity Apache Software Foundation advisory covers CVE-2026-33558 affecting Apache Kafka.

CVE-2026-33558 Published Apr 20, 2026Updated by vendor Jun 17, 2026

CVE-2026-33558

Affected products & platforms

Apache Software FoundationMessagingKafka

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Summary

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 versions

through 3.9.1

Official advisory · medium-confidence parse· fetched 2 months ago·verify at source

Fixed versions

No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.

Official advisory · medium-confidence parse· fetched 2 months ago·verify at source

Mitigation

The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.

Official advisory · medium-confidence parse· fetched 2 months ago·verify at source

Sources

Official and corroborating records used to build this advisory.

NVD discovery recordNVD
Independent discovery and scoring cross-reference. Vendor remediation guidance takes precedence. Discovered from the machine-readable feed https://services.nvd.nist.gov/rest/json/cves/2.0; this link opens the NVD record for CVE-2026-33558 instead of the raw feed document.
NIST National Vulnerability Database

Cross-references

Validate CVE metadata against the authoritative registries.

CVE-2026-33558NVD CVE.org MITRE

Official resources

ASF Security — reporting & CVE process
Official documentation
The Apache Software Foundation's official security page: how ASF CVEs are published and where each project's advisories live.
Apache project downloads (fixed releases)
Official documentation
Official ASF download tree — fetch the fixed release named in this advisory from the project's directory.

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