{"id":"GHSA-28jg-cgg7-j4wc","summary":"Apache Kafka does not validate JWT tokens in its OAUTHBEARER authentication implementation","details":"A 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.\n\nApache advises 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.","aliases":["BIT-kafka-2026-33557","CVE-2026-33557"],"modified":"2026-07-17T21:17:31.701061117Z","published":"2026-04-20T15:31:52Z","database_specific":{"cwe_ids":["CWE-1285"],"severity":"CRITICAL","github_reviewed":true,"github_reviewed_at":"2026-04-24T15:29:31Z","nvd_published_at":"2026-04-20T14:16:18Z"},"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33557"},{"type":"WEB","url":"https://github.com/apache/kafka/commit/01d8e7db8d08dbd538892b409457ea6bfcc2a422"},{"type":"PACKAGE","url":"https://github.com/apache/kafka"},{"type":"WEB","url":"https://kafka.apache.org/cve-list"},{"type":"WEB","url":"https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h"},{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2026/04/17/2"}],"affected":[{"package":{"name":"org.apache.kafka:kafka-clients","ecosystem":"Maven","purl":"pkg:maven/org.apache.kafka/kafka-clients"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.1.0"},{"fixed":"4.1.2"}]}],"versions":["4.1.0","4.1.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-28jg-cgg7-j4wc/GHSA-28jg-cgg7-j4wc.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}