{"id":"CVE-2026-33557","state":"PUBLISHED","title":"Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication","description":"A possible security vulnerability has been identified in Apache Kafka.\n\nBy 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\nWe 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.","publishedAt":"2026-04-20T13:28:43.669Z","updatedAt":"2026-07-15T01:06:14.162Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"CISA-ADP"},"assigner":"apache","products":["Apache Software Foundation Apache Kafka"],"affected":[{"vendor":"Apache Software Foundation","product":"Apache Kafka","defaultStatus":"unaffected","versions":[{"version":"4.1.0","status":"affected","lessThanOrEqual":"4.1.1","versionType":"semver"}]}],"references":["https://kafka.apache.org/cve-list","https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h","http://www.openwall.com/lists/oss-security/2026/04/17/2","https://access.redhat.com/security/cve/CVE-2026-33557","https://bugzilla.redhat.com/show_bug.cgi?id=2459739","https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33557.json"],"weaknesses":["CWE-1285","CWE-303"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/33xxx/CVE-2026-33557.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33557","state":"PUBLISHED","datePublished":"2026-04-20T13:28:43.669Z","dateUpdated":"2026-07-15T01:06:14.162Z","assignerShortName":"apache","assignerOrgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","dateReserved":"2026-03-23T03:14:53.527Z"},"containers":{"cna":{"title":"Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication","descriptions":[{"lang":"en","value":"A possible security vulnerability has been identified in Apache Kafka.\n\nBy 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\nWe 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."}],"affected":[{"vendor":"Apache Software Foundation","product":"Apache Kafka","defaultStatus":"unaffected","versions":[{"version":"4.1.0","status":"affected","lessThanOrEqual":"4.1.1","versionType":"semver"}]}],"references":[{"url":"https://kafka.apache.org/cve-list","tags":["vendor-advisory"]},{"url":"https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h","tags":["mailing-list"]}],"metrics":[{"other":{"content":{"text":"important"},"type":"Textual description of severity"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1285","description":"CWE-1285 Improper Validation of Specified Index, Position, or Offset in Input","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"apache","orgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","dateUpdated":"2026-04-20T13:28:43.669Z"},"credits":[{"lang":"en","type":"finder","value":"Павел Романов <promanov1994@gmail.com>"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/04/17/2"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2026-04-20T13:38:51.117Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":9.1,"attackVector":"NETWORK","baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","integrityImpact":"HIGH","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"NONE","privilegesRequired":"NONE","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-04-20T14:29:31.424817Z","id":"CVE-2026-33557","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-04-20T14:30:30.936Z"}},{"title":"kafka: Apache Kafka: Authentication bypass via improper JWT validation","descriptions":[{"lang":"en","value":"A flaw was found in Apache Kafka. By default, the `sasl.oauthbearer.jwt.validator.class` property is set to `org.apache.kafka.common.security.oauthbearer.DefaultJwtValidator`, which does not validate JSON Web Token (JWT) signatures, issuers, or audiences. A remote attacker can exploit this by crafting a malicious JWT token with an arbitrary `preferred_username`, leading to an authentication bypass and unauthorized access to the Kafka broker."}],"affected":[{"vendor":"Red Hat","product":"OpenShift Serverless","packageName":"openshift-serverless-1/kn-ekb-dispatcher-rhel9","defaultStatus":"unaffected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:serverless:1"]},{"vendor":"Red Hat","product":"OpenShift Serverless","packageName":"openshift-serverless-1/kn-ekb-receiver-rhel9","defaultStatus":"unaffected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:serverless:1"]},{"vendor":"Red Hat","product":"Red Hat build of Apache Camel 4 for Quarkus 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