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Advisory record · GHSA-28jg-cgg7-j4wc

Apache Kafka does not validate JWT tokens in its OAUTHBEARER authentication implementation

CVSS 9.1 CriticalCriticalEPSS 0.0090 · 59th percentile

Critical, because:

  • CVSS score 9.1: 9.0 or more.

How we decide what’s critical

Published by the GitHub Advisory Database at 20 Apr 2026, 15:31 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
org.apache.kafka:kafka-clientsMaven>=4.1.0, <4.1.24.1.2
Identifiers
GHSA-28jg-cgg7-j4wc · BIT-kafka-2026-33557 · CVE-2026-33557
Weakness (CWE)
CWE-303 · CWE-1285
Tags
Published
20 Apr 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Apache Kafka's kafka-clients package, versions 4.1.0 up to but not including 4.1.2, is affected. By default the broker's OAUTHBEARER validator accepts any JWT without checking its signature, issuer, or audience, so an attacker who can reach the broker can forge a token for any user. Upgrade to kafka-clients 4.1.2 or later. Until then, set sasl.oauthbearer.jwt.validator.class to org.apache.kafka.common.security.oauthbearer.BrokerJwtValidator.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
9.1 Critical 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N GitHub Advisory Database
  • CISA KEV Not listed.
  • EPSS 0.0090, the 59th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:17 UTC First seen by agentprime
  2. 31 Oct 2026, 14:17 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.