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This vulnerability in Elasticsearch arises from improper resource allocation limits in the user settings data handling mechanism. Elasticsearch provides API endpoints, such as the cluster settings or user-specific configuration endpoints, where authenticated users can submit data to modify settings. The system does not enforce sufficient size validation or throttling on the input data for these settings. When a low-privileged authenticated user sends a request containing excessively large user settings data—for instance, a massively oversized JSON payload—the Elasticsearch process attempts to allocate memory to parse and store this data. Due to the absence of bounds checking, this triggers uncontrolled memory allocation. The memory consumption can rapidly deplete available system resources, leading to an out-of-memory (OOM) condition. This causes the Elasticsearch service to crash, resulting in a persistent denial of service. The crash may prevent restart if corrupted settings persist, requiring manual intervention. The issue is rooted in CWE-770, where resources are allocated without limits. The attack leverages CAPEC-130, overwhelming system memory through oversized data submission. Exploitation requires network access and valid user credentials, but even low privileges suffice. The vulnerability affects specific versions where the flawed code path is active. Patches introduce size checks and throttling mechanisms to reject oversized submissions before memory allocation.
Platform: Elasticsearch
Version: 8.x, 9.x
Vulnerability: Resource exhaustion DoS
Severity: Moderate
date: 2025-12-19
Prediction: Patch released 2025-12-19
What Undercode Say:
Analytics:
curl -X PUT “localhost:9200/_cluster/settings” -H ‘Content-Type: application/json’ -d ‘{“persistent”:{“”:{“data”:”‘”$(printf ‘%s’ 1000000 ”)”‘”}}}’
grep -i “heap” /etc/elasticsearch/jvm.options
systemctl status elasticsearch
journalctl -u elasticsearch –since “2025-12-19”
netstat -tlnp | grep 9200
ps aux | grep elasticsearch
How Exploit:
Authenticate, send oversized settings payload via API, trigger OOM crash.
Protection from this CVE:
Update to patched versions, implement input size limits, use network segmentation.
Impact:
Persistent denial of service, service outage, memory exhaustion.
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Sources:
Reported By: github.com
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