{"cve":"CVE-2026-33557","nvd":{"published":"2026-04-20T14:16:18.780","modified":"2026-10-26T22:10:00.163","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","score":9.1},"cwes":["CWE-1285","CWE-303"],"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"],"products":["apache:kafka"],"source":"nvd","synced_at":"2026-10-26T22:26:44.656832877+00:00"},"epss":{"cve":"CVE-2026-33557","score":0.00897,"percentile":0.59327,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-28jg-cgg7-j4wc","url":"https://osv.dev/vulnerability/GHSA-28jg-cgg7-j4wc","summary":"Apache Kafka does not validate JWT tokens in its OAUTHBEARER authentication implementation","modified":"2026-09-10T03:50:42.200581867Z","packages":[{"ecosystem":"Maven","name":"org.apache.kafka:kafka-clients","purl":"pkg:maven/org.apache.kafka/kafka-clients","ranges":[">=4.1.0 <4.1.2"],"fixed":["4.1.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}