Overview
The CVE-2025-27818 vulnerability poses a significant threat to Apache Kafka users, with the potential to compromise systems or lead to data leakage. This specific vulnerability pertains to Apache Kafka and Kafka Connect, and opens the door to a potential security loophole if exploited by an attacker. The vulnerability’s severity is underscored by its CVSS Severity Score of 8.8, indicating a high level of risk to affected systems.
This vulnerability matters because it allows for unrestricted deserialization of untrusted data or a remote code execution (RCE) vulnerability when certain gadgets are present in the classpath. This could potentially allow an attacker to execute harmful java deserialization gadget chains on the Kafka connect server, posing a significant threat to the security and integrity of the affected systems.
Vulnerability Summary
CVE ID: CVE-2025-27818
Severity: High (8.8)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: Potential system compromise or data leakage
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Product | Affected Versions
Apache Kafka | 2.0.0 to 3.9.1
Kafka Connect | 2.3.0 to 3.9.1
How the Exploit Works
The vulnerability is rooted in the ability of an attacker to alter configuration settings on the Kafka cluster resource or Kafka Connect worker. By setting the `sasl.jaas.config` property for any of the connector’s Kafka clients to “com.sun.security.auth.module.LdapLoginModule”, the attacker can enable the server to connect to their LDAP server. The server then deserializes the LDAP response, providing the attacker with the means to execute Java deserialization gadget chains on the Kafka connect server. Consequently, this could lead to unrestricted deserialization of untrusted data or a remote code execution (RCE) vulnerability.
Conceptual Example Code
Given the nature of this exploit, the vulnerability might be exploited through a simulated shell command like this:
$ kafka-configs --alter --add-config 'sasl.jaas.config=com.sun.security.auth.module.LdapLoginModule' --entity-type brokers --entity-name 1In the conceptual code above, the attacker alters the Kafka Broker configuration, setting the `sasl.jaas.config` property to the problematic “com.sun.security.auth.module.LdapLoginModule”. This setting enables the server to connect to the attacker’s LDAP server, opening the door to potential Java deserialization attacks.
Mitigation Guidance
To mitigate this vulnerability, we recommend applying the vendor patch or using Web Application Firewall (WAF) or Intrusion Detection System (IDS) as temporary mitigation. Also, it is advisable for Kafka users to validate connector configurations and only allow trusted LDAP configurations. It is prudent to examine connector dependencies for vulnerable versions and either upgrade their connectors, upgrade that specific dependency, or remove the connectors altogether. Users can also implement their own connector client config override policy to control which Kafka client properties can be overridden directly in a connector config and which cannot.