CVE-2025-13653 is a vulnerability identified in floragunn's Search Guard FLX, a security plugin for Elasticsearch that provides access control and encryption features. The flaw affects versions from 3.1.0 up to 4.0.0 when the enterprise modules are disabled, which is common in community or basic deployments. The vulnerability allows authenticated users to craft specific requests that bypass privilege checks and read documents from data streams they should not have access to. This is classified under CWE-200 (Exposure of Sensitive Information) and CWE-863 (Incorrect Authorization). The issue does not require user interaction beyond sending requests, and no elevated privileges beyond authentication are necessary. The CVSS v3.1 base score is 4.3 (medium), reflecting network attack vector, low complexity, and limited impact confined to confidentiality. No integrity or availability impacts are reported. No patches or known exploits are currently available, but the vulnerability poses a risk of unauthorized data disclosure in environments where Search Guard FLX is deployed without enterprise modules. The vulnerability highlights a gap in access control enforcement within the plugin's data stream handling logic, potentially exposing sensitive Elasticsearch documents to unauthorized internal users.

For European organizations, this vulnerability could lead to unauthorized disclosure of sensitive data stored in Elasticsearch clusters protected by Search Guard FLX community editions. Sectors such as finance, healthcare, government, and critical infrastructure that rely on Elasticsearch for data analytics and storage may face confidentiality breaches. Exposure of sensitive documents could result in regulatory non-compliance under GDPR, leading to legal and financial penalties. The impact is limited to users with valid authentication credentials, so insider threats or compromised accounts pose the greatest risk. Since the vulnerability does not affect data integrity or availability, operational disruption is unlikely. However, data leakage could undermine trust and damage organizational reputation. Organizations using enterprise modules are not affected, which reduces the overall risk for deployments with full commercial licensing. The lack of known exploits reduces immediate threat but does not eliminate the risk of future attacks once exploit code becomes available.

European organizations should immediately audit their Search Guard FLX deployments to identify affected versions running without enterprise modules. Restrict user authentication to trusted personnel and enforce strong authentication mechanisms such as multi-factor authentication to reduce risk of credential compromise. Implement strict role-based access controls and minimize privileges granted to users to limit potential data exposure. Monitor Elasticsearch and Search Guard logs for unusual or unauthorized data stream access patterns that could indicate exploitation attempts. Network segmentation and limiting access to Elasticsearch clusters can reduce exposure. Prepare to apply vendor patches or updates as soon as they are released. If possible, consider upgrading to versions with enterprise modules enabled or alternative security solutions that provide robust authorization enforcement. Conduct security awareness training to inform users about the risks of unauthorized data access. Regularly review and update security policies related to Elasticsearch access and data protection.