GHSA-3W6P-8F82-GW8R

Using JMSAppender in log4j configuration may lead to deserialization of untrusted data

Workarounds

1. Do NOT change log4j configuration to use JMSAppender along with insecure JMS broker
2. Alternatively, you can issue below command to remove JMSAppender.class:

# install zip command if you don't have
apt-get update && apt-get install -y zip
# remove the class
zip -d clickhouse-jdbc-bridge*.jar ru/yandex/clickhouse/jdbcbridge/internal/log4j/net/JMSAppender.class

References

Please refer to CVE-2021-4104 to read more.

For more information

If you have any questions or comments about this advisory, please feel free to open an issue in the repository.

ClickHouse JDBC Bridge uses slf4j-log4j12 1.7.32, which depends on log4j 1.2.17. It allows a remote attacker to execute code on the server, if you changed default log4j configuration by adding JMSAppender and an insecure JMS broker.

Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.

GHSA-3W6P-8F82-GW8R has a CVSS score of 8.1 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.0.7); upgrading removes the vulnerable code path.

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The patch version 2.0.7 removed log4j dependency by replacing slf4j-log4j12 to slf4j-jdk14. Logging configuration is also changed from log4j.properties to logging.properties.

1. What is GHSA-3W6P-8F82-GW8R? GHSA-3W6P-8F82-GW8R is a high-severity insecure deserialization vulnerability in ru.yandex.clickhouse:clickhouse-jdbc-bridge (maven), affecting versions < 2.0.7. It is fixed in 2.0.7. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
2. How severe is GHSA-3W6P-8F82-GW8R? GHSA-3W6P-8F82-GW8R has a CVSS score of 8.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of ru.yandex.clickhouse:clickhouse-jdbc-bridge are affected by GHSA-3W6P-8F82-GW8R? ru.yandex.clickhouse:clickhouse-jdbc-bridge (maven) versions < 2.0.7 is affected.
4. Is there a fix for GHSA-3W6P-8F82-GW8R? Yes. GHSA-3W6P-8F82-GW8R is fixed in 2.0.7. Upgrade to this version or later.
5. Is GHSA-3W6P-8F82-GW8R exploitable, and should I be worried? Whether GHSA-3W6P-8F82-GW8R is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-3W6P-8F82-GW8R is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-3W6P-8F82-GW8R? Upgrade ru.yandex.clickhouse:clickhouse-jdbc-bridge to 2.0.7 or later.