Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication_CVE-2026-33557

{
    "lastseen": "",
    "description": "A possible security vulnerability has been identified in Apache Kafka.\n\nBy default, the broker property `sasl.oauthbearer.jwt.validator.class` is\u00a0set to `org.apache.kafka.common.security.oauthbearer.DefaultJwtValidator`. It accepts any JWT token without validating its\u00a0signature, issuer, or audience. An attacker can generate a JWT\u00a0token 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.",
    "published": "2026-04-20T13:28:43.669Z",
    "modified": "2026-04-20T14:30:30.936Z",
    "type": "cve",
    "title": "Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication",
    "source": "apache",
    "references": "https://kafka.apache.org/cve-list\nhttps://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h",
    "id": "CVE-2026-33557",
    "bulletinFamily": "",
    "cwe": [
        "CWE-1285"
    ],
    "cvelist": null,
    "sourceData": "Apache Software Foundation Apache Kafka 4.1.0",
    "sourceHref": "",
    "cvss": {
        "score": 9.1,
        "severity": "CRITICAL",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Apache Kafka",
    "version": "4.1.0",
    "vendor": "Apache Software Foundation",
    "ai_description": "Missing JWT token validation in OAUTHBEARER authentication allows attackers to generate and use fake JWT tokens.",
    "ai_severity": "Critical",
    "ai_vendor": "Apache Software Foundation",
    "ai_product": "Apache Kafka",
    "ai_version": "4.1.0, 4.1.1",
    "ai_score": 9.1
}