Vulnerability · Published Apr 20, 2026 · Assigned by apache
CVE-2026-33558Apache Kafka, Apache Kafka Clients: Information Exposure Through Network Client Log Output
Medium 5.3
In plain English
A medium-severity security flaw in Apache Kafka from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Maven | org.apache.kafka:kafka-clients | 3.9.2 | GHSA-wf66-mphr-4c4r |
| Maven | org.apache.kafka:kafka-clients | 4.0.1 | GHSA-wf66-mphr-4c4r |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Apache Software Foundation | Apache Kafka | 0.11.0 – through 3.9.14.0.0 |
| Apache Software Foundation | Apache Kafka Clients | 0.11.0 – through 3.9.14.0.0 |
Weakness: CWE-533 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N