How severe is CVE-2021-39132?

CVE-2021-39132 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-39132?

CVE-2021-39132 affects the following packages: org.rundeck:rundeck-core (Maven), org.rundeck:rundeck-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-39132?

Update org.rundeck:rundeck-core to 3.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-39132 is resolved across your whole dependency graph.

How do I detect CVE-2021-39132 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.rundeck:rundeck-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-39132 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is CVE-2021-39132 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-39132 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-39132?

CVE-2021-39132 has an EPSS (Exploit Prediction Scoring System) score of 1.7%, placing it in the 76th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-39132?

CVE-2021-39132 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-39132 published, and has it been updated?

CVE-2021-39132 was published on August 30, 2021 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

HIGH severity

CVE-2021-39132 — rundeck-core

HIGHFix: rundeck/rundeck@850d12e

CVE-2021-39132 is a high-severity (CVSS 8.8) Deserialization of Untrusted Data vulnerability in org.rundeck:rundeck-core. A fix is available for org.rundeck:rundeck-core — see the affected versions and patch details below.

YAML deserialization can run untrusted code

Also known asGHSA-q4rf-3fhx-88pf

Published

Aug 30, 2021

Updated

Jul 9, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs76th percentile — riskier than 76% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-39132 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

☕org.rundeck:rundeck-core☕org.rundeck:rundeck-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Impact

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.

Patches

Versions 3.4.3, 3.3.14

Workarounds

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

For more information

If you have any questions or comments about this advisory:

Email us at [email protected]

To report security issues to Rundeck please use the form at https://rundeck.com/security

Reporter: Rojan Rijal from Tinder Red Team

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.rundeck:rundeck-core`	≥ 3.4.0&&< 3.4.3	3.4.3`org.rundeck:rundeck-core:3.4.3`
☕Maven	`org.rundeck:rundeck-core`	all versions	3.3.14`org.rundeck:rundeck-core:3.3.14`

Affected Products

1 product · 4 configurations

Application

rundeckpagerduty

≥ 3.4.0 && < 3.4.3

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.rundeck:rundeck-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.rundeck:rundeck-core to 3.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-39132 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

### Impact 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 typ