CVE catalog
CVE-2026-33557
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.D
- Severity
- Critical · CVSS 9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.90% · Oct 25, 2026
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.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Cpe | kafka | Not reported | 4.1.2 | fixed |
| Ubuntu | kafka | pro | 2.2.0u2-0ubuntu3.1 | vulnerable |
| Ubuntu | kafka | pro | 2.2.0u2-0ubuntu3.2 | vulnerable |
| Ubuntu | kafka | pro | 2.2.2u1-0ubuntu1+esm2 | vulnerable |
| Cpe | kafka | Not reported | 4.1.2 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Cpe | kafka | cpe | Not reported | 4.1.2 | Not reported | Not reported | Not reported |
| Cpe | kafka | cpe | Not reported | 4.1.2 | Not reported | NVD-CVE-2026-33557 | Not reported |
OpenFactory catalog packages
No matching packages in this catalog.
Observed:
References
- [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://kafka.apache.org/cve-list]
- [https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-33557]
- [https://osv.dev/vulnerability/UBUNTU-CVE-2026-33557]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33557.json]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-1723.json]
[CERT-Bund public advisories] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]