Upstream information
Description
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.
SUSE information
Overall state of this security issue: Does not affect SUSE products
This issue is currently rated as having critical severity.
| CVSS detail | CNA (0b0ca135-0b70-47e7-9f44-1890c2a1c46c) | CNA (CISA-ADP) | SUSE |
|---|---|---|---|
| Base Score | 8.6 | 9.1 | 9.1 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality Impact | High | High | High |
| Integrity Impact | Low | High | High |
| Availability Impact | Low | None | None |
| CVSSv3 Version | 3.1 | 3.1 | 3.1 |
SUSE Timeline for this CVE
CVE page created: Thu Oct 29 11:40:14 2026CVE page last modified: Thu Oct 29 11:40:14 2026