CVE-2026-33557

9.1 CRITICAL
Published: April 20, 2026 Modified: April 22, 2026
View on NVD

Description

A possible security vulnerability has been identified in Apache Kafka. By default, the broker property `sasl.oauthbearer.jwt.validator.class` is set to `org.apache.kafka.common.security.oauthbearer.DefaultJwtValidator`. It accepts any JWT token without validating its signature, issuer, or audience. An attacker can generate a JWT token from any issuer with the `preferred_username` set to any user, and the broker will accept it. We advise the Kafka users using kafka v4.1.0 or v4.1.1 to set the config `sasl.oauthbearer.jwt.validator.class` to `org.apache.kafka.common.security.oauthbearer.BrokerJwtValidator` explicitly to avoid this vulnerability. Since Kafka v4.1.2 and v4.2.0 and later, the issue is fixed and will correctly validate the JWT token.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://kafka.apache.org/cve-list
Source: security@apache.org
Vendor Advisory
https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h
Source: security@apache.org
Vendor Advisory Mitigation
http://www.openwall.com/lists/oss-security/2026/04/17/2
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.1 / 10.0
EPSS (Exploit Probability)
0.2%
42th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

apache