Decoding the Update Dilemma: Heap Exhaustion and Permission Puzzles in Wazuh Indexer Service


“Following a recent update to our Wazuh server by the system administrator, we’ve encountered errors when attempting to operate the indexer service. The service status reveals repeated attempts to trigger G1GC due to high heap usage, despite adjustments to the JVM options file setting the heap size to 8G. Additionally, we’re experiencing SSL handshake exceptions related to AEAD cipher fragment buffer insufficiency. Could these issues be related to the JDK update and TLS versions? Moreover, we’ve observed access denied exceptions in the logs, even though the necessary permissions appear to be correctly set. What could be the underlying cause of these problems?”


In the wake of a system administrator’s update to a Wazuh server, a series of perplexing errors have emerged during the operation of the indexer service. The crux of the issue lies in the service’s status logs, which indicate a persistent need to trigger G1 Garbage Collector (G1GC) due to high heap usage. This is despite the heap size being explicitly set to 8GB within the JVM options file. The situation is further complicated by SSL handshake exceptions, specifically citing an “Insufficient buffer remaining for AEAD cipher fragment” error. Additionally, access denied exceptions have been logged, contradicting the apparent correct setting of permissions.

The G1GC is designed to optimize garbage collection in a way that minimizes pause times without compromising throughput. However, when it repeatedly attempts to free memory, it’s a strong indicator that the heap is under pressure. This could be due to memory leaks within the application, or the heap size may still be insufficient for the workload post-update.

SSL Handshake Exceptions

The SSL handshake exceptions related to AEAD cipher fragments suggest a possible misconfiguration or incompatibility introduced with the JDK update. AEAD (Authenticated Encryption with Associated Data) ciphers are a modern class of cipher used in TLS, and they require a specific buffer size to function correctly. An update to the JDK could have altered the way buffer sizes are calculated or enforced, leading to these errors.

Access Denied Exceptions

The access denied exceptions are particularly puzzling, as they imply a file permission issue. However, the logs suggest that the necessary permissions are set correctly. This could point to a problem with the file system, such as SELinux enforcing stricter access controls, or it could be a symptom of a deeper issue within the updated server environment.

Potential Root Causes

Given these symptoms, the underlying cause could be multifaceted. It’s plausible that the JDK update has introduced changes that are not fully compatible with the current configuration of the Wazuh server or the indexer service. This could manifest in both the heap pressure and the SSL configuration issues. The access denied exceptions might be a separate issue, or they could be another symptom of the JDK update’s impact on the system.


To resolve these issues, a systematic approach is required. First, a thorough review of the JDK release notes and the Wazuh server’s update documentation should be conducted to identify any known issues or changes that could affect operation. Next, a rollback to a previous stable version of the JDK could help determine if the update is indeed the cause. Finally, engaging with the Wazuh community or support channels may provide insights from other users who have faced similar challenges.

In summary, while the recent update aimed to enhance the Wazuh server’s capabilities, it has inadvertently introduced a set of challenges that require careful analysis and methodical troubleshooting to overcome. The journey to resolution will be a testament to the robustness of the system and the diligence of its administrators.

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