CVE-2026-33558 | Apache Kafka, Apache Kafka Clients: Information Exposure Through Network Client Log Output

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.

Published: 2026-04-20 Last update: 2026-04-22 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-33558 is rated Low Risk (34/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.16%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-33558

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-22 0.11% 0.16% +0.05%
2 2026-04-23 0.03% 0.11% +0.08%
3 2026-04-21 — 0.03% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-33558

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 1.4 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-33558

GitHub Security Advisory for CVE-2026-33558

GHSA-wf66-mphr-4c4r · Severity: medium · Ecosystem: maven — Apache Kafka exposes sensitive information in its DEBUG logs

OS Trackers for CVE-2026-33558

vendor priority summary link
ubuntu medium CVE-2026-33558 medium priority: Ubuntu including 1 source packages (kafka), 6 status rows across 6 suites (bionic, jammy, noble, questing, resolute, upstream): DNE 4, needs-triage 2. https://ubuntu.com/security/CVE-2026-33558

Affected software / configurations for CVE-2026-33558

Vendor Product Version Raw CPE
apache kafka >= 0.11.0.0, < 3.9.2 cpe:2.3:a:apache:kafka:*:*:*:*:*:*:*:*
apache kafka 4.0.0 cpe:2.3:a:apache:kafka:4.0.0:-:*:*:*:*:*:*
apache kafka 4.0.0 cpe:2.3:a:apache:kafka:4.0.0:rc0:*:*:*:*:*:*
apache kafka 4.0.0 cpe:2.3:a:apache:kafka:4.0.0:rc1:*:*:*:*:*:*
apache kafka 4.0.0 cpe:2.3:a:apache:kafka:4.0.0:rc3:*:*:*:*:*:*

References for CVE-2026-33558

cvelogic Threat Intelligence