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CVE-2025-27818VulnerabilityPublished Updated

CVE-2025-27818: Apache Kafka · Deserialization of Untrusted Data

Affects Apache KafkaSource CVE Database V5

0

Not known to be exploited · CVSS 8.8 High.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.0% chance of exploitation in 30 days – higher than 64% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Jun 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Affected software

ProductAffectedFixed in
Mavenorg.apache.kafka/kafkapkg:maven/org.apache.kafka/kafkaOther threatsAffected
  • =2.3.0
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2025-27818, organizations should: 1) Upgrade Apache Kafka to version 3.9.1 or later, or 4.0.0 or later, where the system property `-Dorg.apache.kafka.disallowed.login.modules` disables dangerous login modules by default. 2) Implement strict connector client config override policies to restrict which Kafka client properties can be overridden in connector configurations, preventing unauthorized setting of `sasl.jaas.config` properties. 3) Audit all connector configurations to ensure that only trusted and validated LDAP configurations are used, avoiding connections to untrusted LDAP servers. 4) Review and update connector dependencies to remove or upgrade any libraries that include unsafe Java deserialization gadgets. 5) Limit alterConfig permissions to trusted administrators and monitor for unusual configuration changes or connector creations. 6) Employ network segmentation and monitoring to detect and block unauthorized LDAP connections initiated by Kafka Connect servers. 7) Regularly review Kafka Connect logs and security alerts for signs of exploitation attempts. These steps go beyond generic advice by focusing on configuration validation, permission management, and dependency auditing specific to this vulnerability.

Description

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.

References

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