A moderate-severity vulnerability in the Hadoop Distributed File System (HDFS) native client could allow attackers to trigger system crashes or corrupt critical data through maliciously crafted URI inputs.
The vulnerability, tracked as CVE-2025-27821, affects Apache Hadoop versions 3.2.0 through 3.4.1. Stems from an out-of-bounds write flaw in the URI parser of the HDFS native client.
This security weakness enables attackers to write data beyond allocated memory boundaries, potentially leading to application crashes, denial-of-service (DoS) attacks, or data corruption.
Technical Impact
The out-of-bounds write vulnerability occurs when the native HDFS client processes specially crafted Uniform Resource Identifiers (URIs).
| CVE ID | Severity | Affected Versions | Component |
|---|---|---|---|
| CVE-2025-27821 | Moderate | 3.2.0 – 3.4.1 | HDFS Native Client |
By exploiting improper bounds checking in the URI parsing logic, attackers can cause the application to write data to unintended memory locations.
This type of memory corruption vulnerability can result in unpredictable system behavior, including service disruptions and potential data integrity issues.
Organizations using HDFS native clients for distributed storage operations face particular risk, as compromised file system operations could affect data reliability across clustered environments.
The vulnerability was discovered and reported by security researcher BUI Ngoc Tan, who received credit for responsible disclosure.
Affected Systems and Mitigation
The vulnerability impacts all Apache Hadoop deployments running versions 3.2.0 through 3.4.1 that utilize the hadoop-hdfs-native-client component.
Apache has classified this as a moderate-severity issue, internally tracked as HDFS-17754. Apache has released Hadoop version 3.4.2 with patches that address the URI parsing flaw.
Organizations are strongly recommended to upgrade to version 3.4.2 immediately to eliminate the vulnerability.
System administrators should prioritize patching HDFS native client installations, particularly in production environments that handle sensitive data or run mission-critical workloads.
According to SecLists advisory, for organizations unable to patch immediately, implement network-level controls to restrict URI inputs.
Monitoring HDFS client logs for unusual parsing errors or crashes can temporarily reduce risk until the upgrade is completed.
The disclosure follows Apache’s standard vulnerability coordination procedures, with full technical details available through the official Apache Hadoop security advisory and CVE database.
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