ghsa-76qp-h5mr-frr4
Vulnerability from github
Published
2025-06-10 09:30
Modified
2025-06-10 20:23
Severity ?
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
Apache Kafka Deserialization of Untrusted Data vulnerability
Details

A possible security vulnerability has been identified in Apache Kafka. This requires access to a alterConfig to the cluster resource, or Kafka Connect worker, and the ability to create/modify connectors on it with an arbitrary Kafka client SASL JAAS config and a SASL-based security protocol, which has been possible on Kafka clusters since Apache Kafka 2.0.0 (Kafka Connect 2.3.0). When configuring the broker via config file or AlterConfig command, or connector via the Kafka Kafka Connect REST API, an authenticated operator can set the sasl.jaas.config property for any of the connector's Kafka clients to "com.sun.security.auth.module.LdapLoginModule", which can be done via the producer.override.sasl.jaas.config, consumer.override.sasl.jaas.config, or admin.override.sasl.jaas.config properties. This will allow the server to connect to the attacker's LDAP server and deserialize the LDAP response, which the attacker can use to execute java deserialization gadget chains on the Kafka connect server. Attacker can cause unrestricted deserialization of untrusted data (or) RCE vulnerability when there are gadgets in the classpath.

Since Apache Kafka 3.0.0, users are allowed to specify these properties in connector configurations for Kafka Connect clusters running with out-of-the-box configurations. Before Apache Kafka 3.0.0, users may not specify these properties unless the Kafka Connect cluster has been reconfigured with a connector client override policy that permits them.

Since Apache Kafka 3.9.1/4.0.0, we have added a system property ("-Dorg.apache.kafka.disallowed.login.modules") to disable the problematic login modules usage in SASL JAAS configuration. Also by default "com.sun.security.auth.module.JndiLoginModule,com.sun.security.auth.module.LdapLoginModule" are disabled in Apache Kafka Connect 3.9.1/4.0.0.

We advise the Kafka users to validate connector configurations and only allow trusted LDAP configurations. Also examine connector dependencies for vulnerable versions and either upgrade their connectors, upgrading that specific dependency, or removing the connectors as options for remediation. Finally, in addition to leveraging the "org.apache.kafka.disallowed.login.modules" system property, Kafka Connect users can also implement their own connector client config override policy, which can be used to control which Kafka client properties can be overridden directly in a connector config and which cannot.

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.apache.kafka:kafka"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.3.0"
            },
            {
              "fixed": "3.9.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-27818"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-06-10T20:23:15Z",
    "nvd_published_at": "2025-06-10T08:15:22Z",
    "severity": "HIGH"
  },
  "details": "A possible security vulnerability has been identified in Apache Kafka.\nThis requires access to a alterConfig to the\u00a0cluster resource, or Kafka Connect worker, and the ability to create/modify connectors on it with an arbitrary Kafka client SASL JAAS config\nand a SASL-based security protocol, which has been possible on Kafka clusters since Apache Kafka 2.0.0 (Kafka Connect 2.3.0).\nWhen configuring the broker via config file or AlterConfig command, or connector via the Kafka Kafka Connect REST API, an authenticated operator\u00a0can set the `sasl.jaas.config`\nproperty for any of the connector\u0027s Kafka clients to \"com.sun.security.auth.module.LdapLoginModule\", which can be done via the\n`producer.override.sasl.jaas.config`, `consumer.override.sasl.jaas.config`, or `admin.override.sasl.jaas.config` properties.\nThis will allow the server to connect to the attacker\u0027s LDAP server\nand deserialize the LDAP response, which the attacker can use to execute java deserialization gadget chains on the Kafka connect server.\nAttacker can cause unrestricted deserialization of untrusted data (or) RCE vulnerability when there are gadgets in the classpath.\n\nSince Apache Kafka 3.0.0, users are allowed to specify these properties in connector configurations for Kafka Connect clusters running with out-of-the-box\nconfigurations. Before Apache Kafka 3.0.0, users may not specify these properties unless the Kafka Connect cluster has been reconfigured with a connector\nclient override policy that permits them.\n\nSince Apache Kafka 3.9.1/4.0.0, we have added a system property (\"-Dorg.apache.kafka.disallowed.login.modules\") to disable the problematic login modules usage\nin SASL JAAS configuration. Also by default \"com.sun.security.auth.module.JndiLoginModule,com.sun.security.auth.module.LdapLoginModule\" are disabled in Apache Kafka Connect 3.9.1/4.0.0. \n\nWe advise the Kafka users to validate connector configurations and only allow trusted LDAP configurations. Also examine connector dependencies for \nvulnerable versions and either upgrade their connectors, upgrading that specific dependency, or removing the connectors as options for remediation. Finally,\nin addition to leveraging the \"org.apache.kafka.disallowed.login.modules\" system property, Kafka Connect users can also implement their own connector\nclient config override policy, which can be used to control which Kafka client properties can be overridden directly in a connector config and which cannot.",
  "id": "GHSA-76qp-h5mr-frr4",
  "modified": "2025-06-10T20:23:15Z",
  "published": "2025-06-10T09:30:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-27818"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/apache/kafka"
    },
    {
      "type": "WEB",
      "url": "https://kafka.apache.org/cve-list"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2025/06/09/2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Apache Kafka Deserialization of Untrusted Data vulnerability"
}


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