CVEvulnerability

CVE-2026-33557

9.1 CRITICAL Published 2026-04-20 Modified 2026-10-26 Official page ↗
Status
Modified
Published
2026-04-20
Last modified
2026-10-26
Assigner
[email protected]
CVSS 3.1 (134c704f-9b21-4f2e-91b3-4a467353bcc0)
9.1 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS 3.1 (0b0ca135-0b70-47e7-9f44-1890c2a1c46c)
8.6 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
Weaknesses
CWE-1285, CWE-303

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.

Affected configurations

• apache kafka (>= 4.1.0 < 4.1.2)

Related

Weakness · CWE (2)

  • CWE-1285 Improper Validation of Specified Index, Position, or Offset in Input weakness
  • CWE-303 Incorrect Implementation of Authentication Algorithm weakness

References