Fluentd collects events from various data sources and writes them to files, RDBMS, NoSQL, IaaS, SaaS, Hadoop and so on. A remote code execution (RCE) vulnerability in non-default configurations of Fluentd allows unauthenticated attackers to execute arbitrary code via specially crafted JSON payloads. Fluentd setups are only affected if the environment variable FLUENT_OJ_OPTION_MODE is explicitly set to object. Please note: The option FLUENT_OJ_OPTION_MODE was introduced in Fluentd version 1.13.2. Earlier versions of Fluentd are not affected by this vulnerability. This issue was patched in version 1.15.3. As a workaround do not use FLUENT_OJ_OPTION_MODE=object.
Weakness
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Fluentd | Fluentd | 1.13.2 (including) | 1.15.3 (excluding) |
Potential Mitigations
- Make fields transient to protect them from deserialization.
- An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.
Related Attack Patterns
References
- https://github.com/fluent/fluentd/commit/48e5b85dab1b6d4c273090d538fc11b3f2fd8135
- https://github.com/fluent/fluentd/security/advisories/GHSA-fppq-mj76-fpj2
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MYD5QV66OLDHES6IKVYYM3Y3YID3VVCO/
- https://github.com/fluent/fluentd/commit/48e5b85dab1b6d4c273090d538fc11b3f2fd8135
- https://github.com/fluent/fluentd/security/advisories/GHSA-fppq-mj76-fpj2
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MYD5QV66OLDHES6IKVYYM3Y3YID3VVCO/