CVE-2025-33042 in Avro Java SDK
Summary
by MITRE • 02/13/2026
Improper Control of Generation of Code ('Code Injection') vulnerability in Apache Avro Java SDK when generating specific records from untrusted Avro schemas.
This issue affects Apache Avro Java SDK: all versions through 1.11.4 and version 1.12.0.
Users are recommended to upgrade to version 1.12.1 or 1.11.5, which fix the issue.
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Analysis
by VulDB Data Team • 04/25/2026
The CVE-2025-33042 vulnerability represents a critical code injection flaw within the Apache Avro Java SDK that fundamentally undermines the security of applications processing untrusted data. This vulnerability resides in the schema generation mechanism where the SDK fails to properly validate and sanitize schema definitions before executing code generation operations. The flaw enables attackers to craft malicious Avro schemas that, when processed by the SDK, can trigger unintended code execution within the application context. Such vulnerabilities are particularly dangerous in enterprise environments where Avro schemas are often dynamically generated or received from external sources, making them prime targets for exploitation through data-driven attacks.
The technical implementation of this vulnerability stems from inadequate input validation within the Avro schema processing pipeline. When the Java SDK encounters specific schema constructs, particularly those involving complex type definitions or custom logical types, it fails to properly isolate or sanitize user-provided schema elements before generating Java code. This improper control of code generation allows attackers to inject malicious code patterns that get executed during the schema compilation phase, effectively bypassing standard security boundaries. The vulnerability manifests when the SDK's code generation component processes schema elements that contain crafted constructs designed to exploit the lack of proper validation controls. This weakness directly maps to CWE-94, which describes improper control of generation of code, and aligns with ATT&CK technique T1059.007 for execution through scripting languages.
The operational impact of this vulnerability extends beyond simple code injection, creating potential pathways for full system compromise within applications that rely on dynamic schema processing. Attackers can leverage this vulnerability to execute arbitrary code on systems processing Avro data, potentially leading to data exfiltration, system persistence, or lateral movement within network environments. The vulnerability affects all versions up to 1.11.4 and specifically version 1.12.0, indicating a prolonged window of exposure that increases the likelihood of successful exploitation. Applications using the affected SDK are particularly vulnerable when they process schemas from untrusted sources, including web services, file uploads, or external data feeds that may contain malicious schema definitions. The attack surface is broad as Avro is commonly used in big data processing frameworks, message queues, and distributed systems where schema evolution and dynamic data handling are fundamental requirements.
Organizations should immediately prioritize upgrading their Apache Avro Java SDK installations to version 1.12.1 or 1.11.5 to remediate this vulnerability. The upgrade process should be carefully coordinated with existing system dependencies to ensure compatibility and prevent operational disruptions. Additional mitigations include implementing strict schema validation policies, deploying network segmentation controls to limit exposure, and establishing monitoring procedures to detect anomalous schema processing activities. Security teams should also consider implementing runtime application self-protection measures and code analysis tools that can detect and block suspicious code generation patterns. The vulnerability's classification as a code injection flaw necessitates comprehensive security testing of all applications that utilize the affected SDK, particularly those handling external data inputs or implementing dynamic schema processing capabilities. Regular security assessments and vulnerability scanning should be conducted to identify any potential exploitation attempts or residual risks associated with the vulnerability.