CVE-2025-27818 identifies a deserialization of untrusted data vulnerability in Apache Kafka that enables authenticated attackers to achieve remote code execution through malicious LDAP server responses by exploiting improper SASL JAAS configuration handling in Kafka Connect workers. This vulnerability affects Apache Kafka versions 2.3.0 through 3.9.0, achieving a CVSS score of 8.8 (High severity) with EPSS percentile of 16.8 indicating significant exploit risk for Java applications utilizing Kafka Connect clusters with SASL authentication configurations. The vulnerability details reveal that authenticated operators with alterConfig permissions can set sasl.jaas.config properties to use com.sun.security.auth.module.LdapLoginModule through connector override configurations, enabling attackers to force Kafka servers to connect to malicious LDAP servers and deserialize untrusted data responses, creating substantial exploit risk for enterprise messaging systems and distributed streaming platforms that rely on Kafka Connect for data integration without proper SASL configuration validation. The root cause analysis reveals that the vulnerability stems from insufficient validation of SASL JAAS login module configurations in Kafka Connect, where inadequate restrictions on LdapLoginModule usage enables deserialization attacks through attacker-controlled LDAP responses, classified as CWE-502 (Deserialization of Untrusted Data). The vulnerability specifically affects SASL authentication processing where producer.override.sasl.jaas.config, consumer.override.sasl.jaas.config, and admin.override.sasl.jaas.config properties can be manipulated to specify dangerous login modules, enabling attackers to exploit known exploited vulnerabilities targeting Java deserialization gadget chains when vulnerable libraries exist in the classpath. Mitigation steps require upgrading to Apache Kafka versions 3.9.1 or 4.0.0 which implement the org.apache.kafka.disallowed.login.modules system property that disables com.sun.security.auth.module.JndiLoginModule and com.sun.security.auth.module.LdapLoginModule by default. Organizations should prioritize identifying Kafka Connect deployments using vulnerable versions, validate all connector configurations to only allow trusted LDAP configurations, examine connector dependencies for vulnerable deserialization gadgets and upgrade or remove problematic connectors, implement custom connector client config override policies to restrict dangerous property overrides, and maintain updated vulnerability database records to track similar deserialization vulnerabilities that could compromise messaging infrastructure through remote code execution attacks and broader security implications for distributed systems handling untrusted data through SASL authentication mechanisms.