CVE-2025-27818
📋 TL;DR
This CVE describes a Java deserialization vulnerability in Apache Kafka Connect that allows authenticated operators with configuration privileges to execute arbitrary code via LDAP login module manipulation. Attackers can achieve remote code execution by configuring connectors to use malicious LDAP servers that trigger deserialization gadget chains. This affects Kafka Connect clusters where users can override SASL JAAS configurations in connector settings.
💻 Affected Systems
- Apache Kafka
- Apache Kafka Connect
📦 What is this software?
Kafka by Apache
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with full compromise of the Kafka Connect server, potentially leading to data exfiltration, lateral movement, or complete system takeover.
Likely Case
Privilege escalation from authenticated operator to full system compromise, enabling data manipulation, credential theft, and persistence mechanisms.
If Mitigated
Limited impact with proper access controls and configuration validation, potentially only allowing denial of service or limited information disclosure.
🎯 Exploit Status
Exploitation requires authenticated access with alterConfig privileges and ability to create/modify connectors. Attack leverages well-known Java deserialization patterns.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apache Kafka 3.9.1/4.0.0
Vendor Advisory: https://kafka.apache.org/cve-list
Restart Required: Yes
Instructions:
1. Upgrade to Apache Kafka 3.9.1 or 4.0.0. 2. Apply the system property '-Dorg.apache.kafka.disallowed.login.modules' if using older versions. 3. Restart Kafka Connect services.
🔧 Temporary Workarounds
Disable vulnerable login modules
allAdd system property to disable LdapLoginModule and JndiLoginModule
-Dorg.apache.kafka.disallowed.login.modules=com.sun.security.auth.module.JndiLoginModule,com.sun.security.auth.module.LdapLoginModule
Implement connector client config override policy
allCreate custom policy to restrict which Kafka client properties can be overridden
Set connector.client.config.override.policy property in Kafka Connect configuration
🧯 If You Can't Patch
- Implement strict access controls to prevent unauthorized users from creating or modifying connectors
- Validate all connector configurations and block any containing LDAP login module configurations
🔍 How to Verify
Check if Vulnerable:
Check if Kafka Connect version is 2.3.0+ and if connector configurations allow sasl.jaas.config overrides with LdapLoginModuleCheck Version:
kafka-topics.sh --version or check Kafka Connect REST API / endpointVerify Fix Applied:
Verify Kafka Connect version is 3.9.1+ or 4.0.0+, and check that system property disallowing login modules is set📡 Detection & Monitoring
Log Indicators:
- Connector configurations containing 'LdapLoginModule'
- Unexpected LDAP connection attempts from Kafka Connect
- Java deserialization errors in logs
Network Indicators:
- Outbound LDAP connections from Kafka Connect to unexpected destinations
- Unusual network traffic patterns from Kafka Connect processes
SIEM Query:
source="kafka-connect" AND ("LdapLoginModule" OR "sasl.jaas.config" OR "com.sun.security.auth.module")