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Apache Kafka exposes sensitive information in its DEBUG logs

Moderate severity GitHub Reviewed Published Apr 20, 2026 to the GitHub Advisory Database • Updated Apr 24, 2026

Package

maven org.apache.kafka:kafka-clients (Maven)

Affected versions

>= 0.11.0, < 3.9.2
= 4.0.0

Patched versions

3.9.2
4.0.1

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. Apache advises Kafka users to upgrade to v3.9.2, v4.0.1, or later to avoid this vulnerability.

References

Published by the National Vulnerability Database Apr 20, 2026
Published to the GitHub Advisory Database Apr 20, 2026
Reviewed Apr 24, 2026
Last updated Apr 24, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(48th percentile)

Weaknesses

Insertion of Sensitive Information into Log File

The product writes sensitive information to a log file. Learn more on MITRE.

CVE ID

CVE-2026-33558

GHSA ID

GHSA-wf66-mphr-4c4r

Source code

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