CVE-2025-33042: Apache Avro Java SDK RCE Vulnerability

CVE-2025-33042 Overview

CVE-2025-33042 is a Code Injection vulnerability affecting the Apache Avro Java SDK. The vulnerability exists in the specific records generation functionality when processing untrusted Avro schemas. An attacker who can control or influence the Avro schema input could potentially inject malicious code during the record generation process, leading to arbitrary code execution within the context of the application.

Critical Impact

Remote attackers can exploit this vulnerability to inject and execute arbitrary code by providing malicious Avro schemas to applications using the vulnerable Apache Avro Java SDK versions.

Affected Products

• Apache Avro Java SDK all versions through 1.11.4
• Apache Avro Java SDK version 1.12.0

Discovery Timeline

• February 13, 2026 - CVE-2025-33042 published to NVD
• February 13, 2026 - Last updated in NVD database

Technical Details for CVE-2025-33042

Vulnerability Analysis

This vulnerability falls under CWE-94 (Improper Control of Generation of Code), commonly known as Code Injection. The flaw resides in how the Apache Avro Java SDK handles schema parsing and specific record generation. When applications process Avro schemas from untrusted sources, insufficient validation allows specially crafted schema definitions to inject arbitrary code into the generated record classes.

The vulnerability is accessible via network-based attack vectors without requiring authentication or user interaction. Successful exploitation can compromise the confidentiality, integrity, and availability of affected systems, though each impact dimension is limited in scope.

Root Cause

The root cause stems from improper control over code generation when the Avro Java SDK creates specific record classes from schema definitions. The schema processing logic does not adequately sanitize or validate schema elements before incorporating them into generated code. This allows attackers to embed malicious code constructs within schema definitions that get executed during the code generation or compilation phase.

Attack Vector

The attack vector is network-based, meaning exploitation can occur remotely without requiring local access to the target system. An attacker would need to supply a malicious Avro schema to an application that uses the vulnerable Apache Avro Java SDK for specific record generation. This could occur in scenarios where:

• Applications accept Avro schemas from external or untrusted sources
• Schema definitions are fetched from remote registries without proper validation
• User-supplied data influences schema generation or parsing

The vulnerability mechanism involves crafting malicious Avro schema definitions that embed code injection payloads. When the vulnerable SDK processes these schemas to generate specific record classes, the injected code becomes part of the generated output and may be executed. For detailed technical analysis, refer to the Apache Security Mailing List Post and Openwall OSS-Security Discussion.

Detection Methods for CVE-2025-33042

Indicators of Compromise

• Unusual or malformed Avro schema files being processed by applications
• Unexpected code execution events originating from Avro schema parsing operations
• Anomalous class file generation or compilation activities in application directories
• Suspicious network connections from applications that process Avro schemas

Detection Strategies

• Monitor application logs for errors or exceptions during Avro schema parsing and record generation
• Implement file integrity monitoring on directories where Avro generates specific record classes
• Deploy runtime application security monitoring to detect code injection attempts
• Audit incoming Avro schemas for suspicious or unexpected code-like constructs

Monitoring Recommendations

• Enable detailed logging for Avro schema processing operations in production environments
• Configure alerts for schema validation failures or parsing anomalies
• Monitor dependency usage to identify applications using vulnerable Apache Avro Java SDK versions
• Implement Software Composition Analysis (SCA) scanning to detect vulnerable library versions

How to Mitigate CVE-2025-33042

Immediate Actions Required

• Upgrade Apache Avro Java SDK to version 1.12.1 or 1.11.5 immediately
• Audit all applications that process Avro schemas from untrusted sources
• Review and restrict schema sources to trusted origins only
• Implement input validation for any externally-supplied Avro schemas

Patch Information

Apache has released patched versions that address this code injection vulnerability. Users are recommended to upgrade to version 1.12.1 (for users on the 1.12.x branch) or version 1.11.5 (for users on the 1.11.x branch). These versions include proper sanitization and validation of schema elements during specific record generation.

For additional details, refer to the Apache Security Mailing List Post.

Workarounds

• Restrict Avro schema processing to only accept schemas from trusted and verified sources
• Implement strict schema validation and sanitization before processing with the Avro SDK
• Run applications that process untrusted schemas in sandboxed or isolated environments
• Consider disabling automatic specific record generation for schemas from external sources until patching is complete

# Maven dependency update example
# Update pom.xml to use patched version:
# For 1.12.x users:
#   <dependency>
#     <groupId>org.apache.avro</groupId>
#     <artifactId>avro</artifactId>
#     <version>1.12.1</version>
#   </dependency>
#
# For 1.11.x users:
#   <dependency>
#     <groupId>org.apache.avro</groupId>
#     <artifactId>avro</artifactId>
#     <version>1.11.5</version>
#   </dependency>