CVE-2026-33557 (GCVE-0-2026-33557)

Vulnerability from cvelistv5 – Published: 2026-04-20 13:28 – Updated: 2026-04-20 14:30
VLAI?
Title
Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication
Summary
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.
Severity ?
No CVSS data available.
CWE
  • CWE-1285 - Improper Validation of Specified Index, Position, or Offset in Input
Assigner
References
Impacted products
Vendor Product Version
Apache Software Foundation Apache Kafka Affected: 4.1.0 , ≤ 4.1.1 (semver)
Create a notification for this product.
Credits
Павел Романов <promanov1994@gmail.com>
Show details on NVD website
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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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