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.
References
| Link | Resource |
|---|---|
| https://kafka.apache.org/cve-list | Vendor Advisory |
| https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h | Vendor Advisory Mitigation |
| http://www.openwall.com/lists/oss-security/2026/04/17/2 | Mailing List |
Configurations
History
22 Apr 2026, 14:14
| Type | Values Removed | Values Added |
|---|---|---|
| CPE | cpe:2.3:a:apache:kafka:*:*:*:*:*:*:*:* | |
| First Time |
Apache kafka
Apache |
|
| References | () https://kafka.apache.org/cve-list - Vendor Advisory | |
| References | () https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h - Vendor Advisory, Mitigation | |
| References | () http://www.openwall.com/lists/oss-security/2026/04/17/2 - Mailing List |
20 Apr 2026, 16:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 9.1 |
20 Apr 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-04-20 14:16
Updated : 2026-04-22 14:14
NVD link : CVE-2026-33557
Mitre link : CVE-2026-33557
CVE.ORG link : CVE-2026-33557
JSON object : View
Products Affected
apache
- kafka
CWE
CWE-1285
Improper Validation of Specified Index, Position, or Offset in Input