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CVE-2026-33557

Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication

Published: Apr 20, 2026Updated: Apr 22, 2026 Sources: CVE List NVDCWE-1285
NVD MITRE
9.1CVSSCRITICAL
EPSS Score
0.5%
Top 61.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-1285

Affected Products

Apache KafkaApache Software Foundation
On-premDatabase
Databases / cache-message-queue
kafkaapache
On-premDatabase
Databases / cache-message-queue
apache software foundationoss-projectUSWeb & CMS Pluginsaka apache foundation
apacheoss-projectUSWeb & CMS Pluginsaka apache http server, apache httpd

Exploitability

Official Patch Available

References

https://kafka.apache.org/cve-list
kafka.apache.org
https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h
lists.apache.org
http://www.openwall.com/lists/oss-security/2026/04/17/2
openwall.com

Timeline

Published
Apr 20, 2026
Last Updated
Apr 22, 2026

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