CVE-2026-335579.1CriticalCWE-1285

CVE-2026-33557: Apache Kafka: Missing JWT token validation in OAUTHBEARER authentication

Apache Software Foundation · Apache Kafka

Vendor fix available · Affected: Apache Software Foundation Apache Kafka · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.9%probability of exploitation in the next 30 days

60th percentile

050100

Higher than 60% of scored CVEs

9.1CriticalCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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 products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

Apache Software Foundation · Apache Kafkafrom 4.1.0 up to and including 4.1.1

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Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Validation of Specified Index, Position, or Offset in Input · Input Validation and Logic
Vendor: Apache Software Foundation
Published: April 2026
Band: Unlikely (under 1%), April 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-33557 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.