Overview
CVE-2025-9624 details a Denial of Service (DoS) vulnerability affecting OpenSearch. This vulnerability allows a remote attacker to trigger a DoS condition by sending specially crafted, complex query_string inputs to the OpenSearch server. Successful exploitation of this vulnerability can render the OpenSearch service unavailable, impacting applications and services that rely on it.
The vulnerability affects all OpenSearch versions prior to 3.2.0. Immediate action is recommended to mitigate the risk.
Technical Details
The vulnerability stems from insufficient validation and processing of the query_string parameter within OpenSearch’s search API. Attackers can craft overly complex or deeply nested queries that consume excessive resources, leading to performance degradation and, ultimately, a denial of service. While the exact nature of the complex queries can vary, they generally involve intricate combinations of boolean operators, wildcards, or regular expressions that overwhelm the query parser and execution engine.
Specifically, the vulnerable code resides in the component responsible for parsing and executing search queries. By exploiting this flaw, an attacker can force the OpenSearch node to exhaust its CPU or memory resources.
CVSS Analysis
Currently, the CVSS score for CVE-2025-9624 is N/A. While the exact score is unavailable, the impact of a DoS vulnerability should not be underestimated. Denial of Service can disrupt critical services and negatively impact business operations. A CVSS score will be updated as information becomes available.
Possible Impact
The successful exploitation of CVE-2025-9624 can have significant consequences:
- Service Disruption: OpenSearch service becomes unavailable, impacting applications that rely on its search and analytics capabilities.
- Data Inaccessibility: Users may be unable to access or query data stored within OpenSearch.
- Reputational Damage: Prolonged service outages can damage the reputation of organizations relying on OpenSearch.
- Financial Loss: Service disruption can lead to financial losses due to downtime and recovery efforts.
Mitigation or Patch Steps
The primary mitigation strategy is to upgrade OpenSearch to version 3.2.0 or later. This version contains a patch that addresses the vulnerability. Follow these steps to mitigate the risk:
- Upgrade OpenSearch: Immediately upgrade all OpenSearch instances to version 3.2.0 or later. Refer to the official OpenSearch documentation for upgrade instructions.
- Input Validation (If Upgrade Not Immediately Possible): Implement strict input validation rules on the
query_stringparameter. Limit the complexity and size of queries allowed. This is a temporary workaround and should not be considered a replacement for upgrading. - Rate Limiting: Implement rate limiting to restrict the number of requests from a single source within a given timeframe. This can help prevent attackers from overwhelming the system with malicious queries.
- Monitoring: Monitor OpenSearch resources (CPU, memory) for unusual activity. Configure alerts to notify administrators of potential DoS attacks.
