# Logstash 8.19.10, 9.1.10, 9.2.4 Security Update (ESA-2026-06)

**URL:** <https://discuss.elastic.co/t/logstash-8-19-10-9-1-10-9-2-4-security-update-esa-2026-06/385531>\
**Category:** Security Announcements\
**Created:** [March 19, 2026, 4:53pm UTC](https://discuss.elastic.co/t/logstash-8-19-10-9-1-10-9-2-4-security-update-esa-2026-06/385531 "2026-03-19T16:53:51Z")\
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**Author:** ![ismisepaul](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ismisepaul/32/102235_2.png) [@ismisepaul](https://discuss.elastic.co/u/ismisepaul)\
**Post date:** [March 19, 2026, 4:53pm UTC](https://discuss.elastic.co/t/logstash-8-19-10-9-1-10-9-2-4-security-update-esa-2026-06/385531/1 "2026-03-19T16:53:51Z")

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**Sensitive Information in Resource Not Removed Before Reuse in Logstash Leading to Access to Sensitive Information**

Dependency on Vulnerable Third-Party Component (CWE-1395) exists in org.lz4:lz4-java decompression library used by logstash-integration-kafka plugin in Logstash that could allow an attacker to access sensitive information from previous buffer contents via Input Data Manipulation (CAPEC-153). Exploitation requires the attacker to produce specially crafted, malformed compressed input to a Kafka topic consumed by Logstash, causing the decompression process to expose residual data from reused output buffers that were not cleared between operations - CVE-2025-66566.

**Affected Versions:**

- 8.x: All versions from 8.15.0 up to and including 8.19.9
- 9.x:
  - All versions from 9.0.0 up to and including 9.1.9
  - All versions from 9.2.0 up to and including 9.2.3

**Affected Configurations:**  
This vulnerability is limited to Logstash deployments that have the logstash-integration-kafka plugin configured to consume from a Kafka topic to which the attacker can publish messages. The attacker requires network access to the Kafka cluster and sufficient Kafka-level permissions (e.g., Kafka ACLs, if configured) to publish messages to the target topic.

**Solutions and Mitigations:**

The issue is resolved in version 8.19.10, 9.1.10, 9.2.4.

**For Users that Cannot Upgrade:**

The attacker requires network access to the Kafka cluster and sufficient Kafka-level permissions (e.g., Kafka ACLs, if configured) to publish messages to the target topic.

Manually update the logstash-integration-kafka plugin to version 11.8.1 or higher using: bin/logstash-plugin update logstash-integration-kafka

**Severity:** CVSSv3.1: Medium ( 5.9 ) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N  
**CVE ID** : CVE-2025-66566  
**Problem Type:** CWE-226 - Sensitive Information in Resource Not Removed Before Reuse  
**Impact:** CAPEC-153 - Input Data Manipulation

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_[View the full topic](https://discuss.elastic.co/t/logstash-8-19-10-9-1-10-9-2-4-security-update-esa-2026-06/385531)._