# CVE-2023-25194: Apache Kafka Connect API: Possible RCE/Denial of service attack via SASL JAAS JndiLoginModule configuration using Kafka Connect

- Exploited (CISA KEV): no
- Published: 2023-02-07
- CVSS: 8.8 HIGH (v3.1)
- EPSS: 95.8% (100th percentile)
- CWE: CWE-502

A possible security vulnerability has been identified in Apache Kafka Connect API.
This requires access to a 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 Connect clusters since Apache Kafka Connect 2.3.0.
When configuring the connector via the 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.JndiLoginModule", 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 3.4.0, 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" is disabled in Apache Kafka Connect 3.4.0. 

We advise the Kafka Connect users to validate connector configurations and only allow trusted JNDI 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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2025-08-18 | 923 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | Before feed history | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2023-04-11 | 63 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### Cloudflare

- 2025-08-18 · new · rule d62935357ff846d9adefb58108ac45b3 · default Block
  > Apache Druid - Remote Code Execution - CVE:CVE-2023-25194. Previous action: Log. New action: Block. This is a New Detection
  Source: https://developers.cloudflare.com/changelog/post/2025-08-18-waf-release/

### F5

- 2023-04-11 · new · rule 200104854
  > Added: signature 200104854 "Apache Kafka Connect JNDI Deserialization" (Server Side Code Injection, risk High), systems: Other Web Server, Proxy Servers. References: CVE-2023-25194.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2024-03-12 · new · rule 200104926
  > Added: signature 200104926 "SSTI gadget - com.sun.security.auth.module.JndiLoginModule (Parameter)" (Server Side Code Injection, risk High), systems: Java Servlets/JSP, Apache, BEA Systems WebLogic Server, IBM WebSphere, JBoss, JavaServer Faces (JSF). References: CVE-2023-25194.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2024-03-12 · new · rule 200104927
  > Added: signature 200104927 "SSTI gadget - com.sun.security.auth.module.JndiLoginModule (Header)" (Server Side Code Injection, risk High), systems: Java Servlets/JSP, Apache, BEA Systems WebLogic Server, IBM WebSphere, JBoss, JavaServer Faces (JSF). References: CVE-2023-25194.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2024-05-21 · new · rule 200104926
  > Added: signature 200104926 "SSTI gadget - com.sun.security.auth.module.JndiLoginModule (Parameter)" (Server Side Code Injection, risk High), systems: Java Servlets/JSP, Apache, BEA Systems WebLogic Server, IBM WebSphere, JBoss, JavaServer Faces (JSF). References: CVE-2023-25194.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2024-05-21 · new · rule 200104927
  > Added: signature 200104927 "SSTI gadget - com.sun.security.auth.module.JndiLoginModule (Header)" (Server Side Code Injection, risk High), systems: Java Servlets/JSP, Apache, BEA Systems WebLogic Server, IBM WebSphere, JBoss, JavaServer Faces (JSF). References: CVE-2023-25194.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: passed (0 of 1 requests blocked), template CVE-2023-25194, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: blocked (1 of 1 requests blocked), template CVE-2023-25194, 2026-11-02

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

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