CVE-2021-39132

YAML deserialization can run untrusted code

Workarounds

Please visit https://rundeck.com/security for information about specific workarounds.

For more information

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Reporter: Rojan Rijal from Tinder Red Team

An authorized user can upload a zip-format plugin with a crafted plugin.yaml, or a crafted aclpolicy yaml file, or upload an untrusted project archive with a crafted aclpolicy yaml file, that can cause the server to run untrusted code on Rundeck Community or Enterprise Edition. An authenticated user can make a POST request, that can cause the server to run untrusted code on Rundeck Enterprise Edition.

The zip-format plugin issues requires authentication and authorization to these access levels, and affects all Rundeck editions:

• admin level access to the system resource type

The ACL Policy yaml file upload issues requires authentication and authorization to these access levels, and affects all Rundeck editions:

• create update or admin level access to a project_acl resource
• create update or admin level access to the system_acl resource

The unauthorized POST request requires authentication, but no specific authorization, and affects Rundeck Enterprise only.

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.

CVE-2021-39132 has a CVSS score of 8.8 (Medium). The vector is network-reachable, low 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 (3.4.3, 3.3.14); upgrading removes the vulnerable code path.

Kodem intelligence

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Versions 3.4.3, 3.3.14

1. What is CVE-2021-39132? CVE-2021-39132 is a medium-severity insecure deserialization vulnerability in org.rundeck:rundeck-core (maven), affecting versions >= 3.4.0, < 3.4.3. It is fixed in 3.4.3, 3.3.14. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
2. How severe is CVE-2021-39132? CVE-2021-39132 has a CVSS score of 8.8 (Medium). 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 org.rundeck:rundeck-core are affected by CVE-2021-39132? org.rundeck:rundeck-core (maven) versions >= 3.4.0, < 3.4.3 is affected.
4. Is there a fix for CVE-2021-39132? Yes. CVE-2021-39132 is fixed in 3.4.3, 3.3.14. Upgrade to this version or later.
5. Is CVE-2021-39132 exploitable, and should I be worried? Whether CVE-2021-39132 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 CVE-2021-39132 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 CVE-2021-39132?
   • Upgrade org.rundeck:rundeck-core to 3.4.3 or later
   • Upgrade org.rundeck:rundeck-core to 3.3.14 or later

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