CVE-2025-37727
📋 TL;DR
This vulnerability allows sensitive information to be exposed in Elasticsearch log files when auditing requests to the reindex API. Attackers with access to log files could potentially extract confidential data. This affects Elasticsearch deployments with auditing enabled that process reindex API requests containing sensitive information.
💻 Affected Systems
- Elasticsearch
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain access to log files containing sensitive data from reindex operations, potentially exposing credentials, PII, or other confidential information stored in Elasticsearch indices.
Likely Case
Unauthorized users with log file access extract limited sensitive information from reindex operations, leading to data exposure but not system compromise.
If Mitigated
With proper log file permissions and access controls, the impact is minimal as only authorized administrators can access logs.
🎯 Exploit Status
Exploitation requires access to log files and specific conditions where sensitive data is processed through reindex API with auditing enabled.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Elasticsearch 8.18.8, 8.19.5, 9.0.8, 9.1.5
Vendor Advisory: https://discuss.elastic.co/t/elasticsearch-8-18-8-8-19-5-9-0-8-9-1-5-security-update-esa-2025-18/382453
Restart Required: No
Instructions:
1. Identify your Elasticsearch version. 2. Upgrade to patched version: 8.18.8, 8.19.5, 9.0.8, or 9.1.5. 3. Follow Elasticsearch upgrade procedures. 4. Verify the update completed successfully.
🔧 Temporary Workarounds
Disable auditing for reindex API
allTemporarily disable auditing specifically for reindex API operations to prevent sensitive data logging
Update Elasticsearch audit configuration to exclude reindex API events
Restrict log file access
linuxImplement strict file permissions and access controls on Elasticsearch log directories
chmod 640 /var/log/elasticsearch/*
chown elasticsearch:elasticsearch /var/log/elasticsearch/*
🧯 If You Can't Patch
- Disable auditing entirely if not required for compliance
- Implement strict access controls on log storage and review log file permissions
🔍 How to Verify
Check if Vulnerable:
Check if auditing is enabled and Elasticsearch version is vulnerable by examining configuration and versionCheck Version:
curl -X GET "localhost:9200" | grep numberVerify Fix Applied:
Verify Elasticsearch version is 8.18.8, 8.19.5, 9.0.8, or 9.1.5 or later📡 Detection & Monitoring
Log Indicators:
- Sensitive data appearing in audit logs
- Reindex API requests in logs containing credentials or PII
Network Indicators:
- Unauthorized access attempts to log file locations
SIEM Query:
source="elasticsearch-audit.log" AND "reindex" AND ("password" OR "token" OR "secret")