CVE-2025-27821
Apache · Apache Hadoop HDFS Native Client
A high-severity vulnerability has been identified in the Apache Hadoop HDFS native client, which could allow an unauthenticated, remote attacker to cause a denial of service or execute arbitrary code.
Executive summary
A high-severity vulnerability has been identified in the Apache Hadoop HDFS native client, which could allow an unauthenticated, remote attacker to cause a denial of service or execute arbitrary code. The flaw is an Out-of-bounds Write, meaning an attacker can send specially crafted data that forces the client application to write to an unintended memory location. Successful exploitation could lead to application crashes, data corruption, or complete system compromise on the machine running the client.
Vulnerability
This vulnerability is an Out-of-bounds Write (CWE-787) within the Apache Hadoop HDFS native client library. An attacker can exploit this flaw by sending a specially crafted request or data packet to an application utilizing the client. When the client processes this malicious input, it fails to properly validate the boundaries of a memory buffer, allowing it to write data beyond the allocated space. This can corrupt adjacent memory, including critical data structures, function pointers, or stack information, leading to unpredictable behavior, application termination (Denial of Service), or hijacking of the program's control flow to achieve arbitrary code execution in the security context of the user running the client application.
Business impact
This vulnerability is rated as High severity with a CVSS score of 7.3. Exploitation poses a significant risk to business operations that rely on Hadoop for big data processing and storage. A successful attack could result in a denial-of-service condition, crashing critical analytics jobs and data ingestion pipelines, leading to operational downtime and potential data loss. If an attacker achieves arbitrary code execution, they could compromise the client system, leading to the theft of sensitive data, lateral movement within the network, or the deployment of ransomware, causing severe financial and reputational damage.
Remediation
Immediate Action: The primary remediation is to apply the security updates provided by the vendor (Apache Software Foundation) to all systems using the affected HDFS native client. After patching, it is crucial to monitor system and application logs for any signs of instability or compromise that may have occurred prior to the update. A review of historical access logs for anomalous requests should also be conducted to identify potential past exploitation attempts.
Proactive Monitoring: Implement enhanced monitoring on systems running the HDFS native client. Security teams should look for crash dumps or error logs related to the client application, which could indicate failed exploitation attempts. Monitor network traffic for malformed HDFS requests and utilize Endpoint Detection and Response (EDR) solutions to detect suspicious process behavior, memory anomalies, or unauthorized command execution on client machines.
Compensating Controls: If immediate patching is not feasible, implement the following controls to reduce risk:
- Network Segmentation: Restrict network access to the HDFS cluster, ensuring that only trusted and authorized clients can connect.
- Input Sanitization: Where possible, use application-level firewalls or proxies to inspect and sanitize data being sent to the HDFS client.
- Principle of Least Privilege: Ensure the application utilizing the HDFS client runs with the minimum permissions necessary to perform its function, limiting the potential impact of a successful code execution exploit.
Exploitation status
Public Exploit Available: false
Analyst recommendation
This vulnerability presents a high risk to the availability, integrity, and confidentiality of data and systems interacting with your Hadoop environment. We strongly recommend that organizations prioritize the immediate application of vendor-supplied security patches across all systems using the affected HDFS native client. While this CVE is not currently on the CISA Known Exploited Vulnerabilities (KEV) catalog, its high severity score and the potential for remote code execution demand urgent attention. Asset owners should immediately identify all vulnerable instances, apply patches, and implement the proactive monitoring and compensating controls outlined in this report to mitigate risk.