CVE-2026-27134
Improper mTLS CA Validation in Strimzi Kafka Causes Authentication Bypass
Publication date: 2026-02-21
Last updated on: 2026-02-25
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linuxfoundation | strimzi_kafka_operator | From 0.49.0 (inc) to 0.50.1 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-287 | When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. |
| CWE-296 | The product does not follow, or incorrectly follows, the chain of trust for a certificate back to a trusted root certificate, resulting in incorrect trust of any resource that is associated with that certificate. |
| CWE-295 | The product does not validate, or incorrectly validates, a certificate. |
Attack-Flow Graph
AI Powered Q&A
How can this vulnerability impact me? :
This vulnerability can impact you by allowing unauthorized users to authenticate to the Kafka cluster if they possess a certificate signed by any CA in the multistage CA chain. Because Strimzi trusts all CAs in the chain, users with certificates from any CA in the chain can gain access.
This can lead to a compromise of confidentiality, integrity, and availability of the Kafka cluster, as unauthorized users could potentially access sensitive data, interfere with broker replication and control plane communication, or disrupt services.
The vulnerability has a high severity with a CVSS v3.1 base score of 8.1, indicating significant potential impact.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade your Strimzi Kafka Operator to version 0.50.1 or later, where the issue has been fixed.
If upgrading immediately is not possible, as a workaround, provide only the single Certificate Authority (CA) that should be trusted instead of the full multistage CA chain when configuring the custom Cluster or Clients CA.
Can you explain this vulnerability to me?
CVE-2026-27134 is a vulnerability in Strimzi Kafka Operator versions 0.49.0 through 0.50.0 related to the handling of custom Certificate Authority (CA) chains used for mutual TLS (mTLS) authentication. When a custom Cluster or Clients CA is configured with a multistage CA chain containing multiple CAs, Strimzi incorrectly trusts all CAs in the chain for mTLS authentication on both internal and user-configured listeners.
This misconfiguration allows any user with a certificate signed by any CA in the chain to authenticate successfully, even if they should not be trusted. The issue only affects users using a custom CA with multiple CAs in the chain and does not affect those using Strimzi-managed CAs or a single CA.
The vulnerability was fixed in Strimzi version 0.50.1, and a workaround is to provide only the single CA intended for trust instead of the full CA chain.