CVE-2024-31141: Apache Kafka Privilege Escalation Flaw

CVE-2024-31141 Overview

CVE-2024-31141 is an Improper Privilege Management and Files or Directories Accessible to External Parties vulnerability affecting Apache Kafka Clients. The vulnerability exists in the ConfigProvider plugin system, which allows customization of Kafka client behavior through configuration data. Apache Kafka provides FileConfigProvider, DirectoryConfigProvider, and EnvVarConfigProvider implementations that can read from disk or environment variables.

In applications where Apache Kafka Clients configurations can be specified by an untrusted party, attackers may exploit these ConfigProviders to read arbitrary contents of the disk and environment variables. This flaw is particularly dangerous in Apache Kafka Connect deployments, where it can be used to escalate from REST API access to filesystem and environment access—a significant concern in SaaS products and multi-tenant environments.

Critical Impact

Attackers with the ability to modify Kafka client configurations can read arbitrary files from the filesystem and access environment variables, potentially exposing sensitive credentials, API keys, and confidential configuration data.

Affected Products

• Apache Kafka Clients versions 2.3.0 through 3.5.2
• Apache Kafka Clients version 3.6.2
• Apache Kafka Clients version 3.7.0

Discovery Timeline

• 2024-11-19 - CVE CVE-2024-31141 published to NVD
• 2025-07-15 - Last updated in NVD database

Technical Details for CVE-2024-31141

Vulnerability Analysis

This vulnerability stems from the trust model of Apache Kafka's ConfigProvider architecture. The ConfigProvider plugins are designed to dynamically retrieve configuration values from various sources, providing flexibility for deployments that need to integrate with external secret management systems or configuration stores.

The FileConfigProvider allows reading configuration values from files on disk, DirectoryConfigProvider reads all files within a specified directory, and EnvVarConfigProvider retrieves values from environment variables. While these features are legitimate for trusted deployment scenarios, they become dangerous when untrusted parties can influence Kafka client configurations.

In Apache Kafka Connect environments, the REST API allows users to create and configure connectors. An attacker with REST API access can craft malicious connector configurations that leverage these ConfigProviders to exfiltrate sensitive data from the underlying system. This effectively transforms limited REST API access into broad filesystem and environment access.

Root Cause

The root cause is improper privilege management in the ConfigProvider plugin system (CWE-269). The ConfigProviders were designed without adequate consideration for scenarios where configuration input might come from untrusted sources. There are no built-in restrictions on which files or environment variables can be accessed, and the providers operate with the full permissions of the Kafka process.

The vulnerability is exacerbated in Apache Kafka Connect, where the REST API provides a convenient attack surface. The lack of default restrictions on ConfigProvider operations means that any user with connector creation privileges can potentially access arbitrary system resources.

Attack Vector

The attack is network-accessible and requires low privileges—specifically, the ability to submit Kafka client configurations. The attacker does not need user interaction to exploit this vulnerability. The attack flow typically involves:

1. The attacker identifies an application or service using vulnerable Apache Kafka Clients where they can influence configuration parameters
2. The attacker crafts a malicious configuration using one of the built-in ConfigProviders (e.g., FileConfigProvider, DirectoryConfigProvider, or EnvVarConfigProvider)
3. The ConfigProvider retrieves the contents of the specified file or environment variable
4. The sensitive data is returned as a configuration value, which may be logged, returned in error messages, or otherwise accessible to the attacker

In Apache Kafka Connect environments, this can be achieved by creating a connector with a malicious configuration through the REST API. The connector configuration can reference sensitive files such as /etc/passwd, application credentials, or cloud provider metadata endpoints.

Detection Methods for CVE-2024-31141

Indicators of Compromise

• Unusual Kafka Connect connector configurations referencing system files like /etc/passwd, /etc/shadow, or cloud metadata endpoints
• Connector configurations using FileConfigProvider, DirectoryConfigProvider, or EnvVarConfigProvider with unexpected file paths or environment variable names
• REST API requests to Kafka Connect containing ConfigProvider references to sensitive directories or credential files
• Unexpected access patterns to sensitive files from Kafka-related processes

Detection Strategies

• Monitor Kafka Connect REST API logs for connector creation or update requests containing ConfigProvider directives referencing sensitive paths
• Implement application-layer logging to track ConfigProvider invocations and the resources they access
• Review existing connector configurations for suspicious use of file-based or environment ConfigProviders
• Deploy file integrity monitoring on sensitive configuration files and directories to detect unauthorized access

Monitoring Recommendations

• Enable verbose logging for Kafka Connect REST API operations and audit all connector configuration changes
• Implement alerting on Kafka process file access patterns, particularly for sensitive system files and credential stores
• Monitor for unusual environment variable access patterns from Kafka-related processes
• Establish baseline connector configurations and alert on deviations that introduce ConfigProvider directives

How to Mitigate CVE-2024-31141

Immediate Actions Required

• Upgrade kafka-clients to version 3.8.0 or later, which includes security fixes for this vulnerability
• Set the JVM system property org.apache.kafka.automatic.config.providers=none to disable automatic ConfigProvider loading in affected versions
• For Kafka Connect deployments, configure allowlist.pattern and allowed.paths properties to restrict ConfigProvider operations to approved resources
• Review existing connector configurations and remove any that use ConfigProviders with overly broad file or environment access

Patch Information

Apache has released Kafka Clients version 3.8.0, which addresses this vulnerability. Users running affected versions (2.3.0 through 3.5.2, 3.6.2, or 3.7.0) should upgrade immediately. The Apache Mailing List Thread contains the official security advisory with detailed upgrade guidance.

For users unable to upgrade immediately, the recommended mitigation is to set the JVM system property to disable automatic ConfigProvider loading. Additionally, NetApp Security Advisory provides guidance for affected NetApp products.

Note: For users of Kafka Clients or Kafka Connect in trusted environments where disk and environment variable access is expected, setting the system property is not recommended as it may break legitimate functionality. Similarly, for Kafka Broker, Kafka MirrorMaker 2.0, Kafka Streams, and Kafka command-line tools, the system property should not be set.

Workarounds

• Set the JVM system property -Dorg.apache.kafka.automatic.config.providers=none to disable automatic ConfigProvider registration
• Configure allowlist.pattern in ConfigProvider implementations to restrict accessible resources to known-safe patterns
• Use allowed.paths configuration to limit file access to specific directories required for legitimate operations
• Implement network segmentation to restrict REST API access to trusted administrative networks only

# Configuration example
# Disable automatic ConfigProvider loading (add to JVM startup arguments)
KAFKA_OPTS="-Dorg.apache.kafka.automatic.config.providers=none"

# For Kafka Connect worker configuration, restrict ConfigProvider access:
# In connect-distributed.properties or connect-standalone.properties
config.providers=file
config.providers.file.class=org.apache.kafka.common.config.provider.FileConfigProvider
config.providers.file.param.allowed.paths=/opt/kafka/config