How severe is CVE-2026-33558?

CVE-2026-33558 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-33558 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33558?

CVE-2026-33558 primarily affects Apache Kafka. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-33558?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-33558 have an EU (EUVD) identifier?

Yes. CVE-2026-33558 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23849.

When was CVE-2026-33558 published?

CVE-2026-33558 was published on 2026-04-20 and last updated on 2026-06-17.

CVE-2026-33558

CVE-2026-33558 is a medium-severity vulnerability in Apache Kafka with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-533.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23849
Weakness: CWE-533
Affected product: Apache Kafka
Published: 2026-04-20
Last modified: 2026-06-17

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.

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 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-33558 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33558?: CVE-2026-33558 primarily affects Apache Kafka. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-33558?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-33558 have an EU (EUVD) identifier?: Yes. CVE-2026-33558 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23849.
When was CVE-2026-33558 published?: CVE-2026-33558 was published on 2026-04-20 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:apache:kafka:*:*:*:*:*:*:*:*
cpe:2.3:a:apache:kafka:4.0.0:-:*:*:*:*:*:*
cpe:2.3:a:apache:kafka:4.0.0:rc0:*:*:*:*:*:*
cpe:2.3:a:apache:kafka:4.0.0:rc1:*:*:*:*:*:*
cpe:2.3:a:apache:kafka:4.0.0:rc3:*:*:*:*:*:*

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