How severe is CVE-2021-21430?

CVE-2021-21430 has a CVSS score of 5.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-21430?

CVE-2021-21430 affects the following packages: org.openapitools:openapi-generator (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-21430?

Update org.openapitools:openapi-generator to 5.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21430 is resolved across your whole dependency graph.

How do I detect CVE-2021-21430 in my Maven dependencies?

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

How do I mitigate CVE-2021-21430 if there is no patch (or I can't update yet)?

Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.

Is CVE-2021-21430 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-21430, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-21430?

CVE-2021-21430 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 33th 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-2021-21430?

CVE-2021-21430 is classified as Improper Privilege Management (CWE-269), CWE-668 (CWE-668). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-21430 published, and has it been updated?

CVE-2021-21430 was published on May 10, 2021 and was last updated on October 20, 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

MEDIUM severity

CVE-2021-21430 — openapi-generator

MEDIUMFix: OpenAPITools/openapi-generator#8787

CVE-2021-21430 is a medium-severity (CVSS 5.5) Improper Privilege Management vulnerability in org.openapitools:openapi-generator. 1 public exploit reference exists, so weaponization risk is real. A fix is available for org.openapitools:openapi-generator — see the affected versions and patch details below.

Creation of Temporary File in Directory with Insecure Permissions in auto-generated Java, Scala code

Also known asGHSA-cqxr-xf2w-943w

Published

May 10, 2021

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs33th percentile — riskier than 33% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2021-21430 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

☕org.openapitools:openapi-generator

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

This vulnerability impacts generated code. If this code was generated as a one-off occasion, not as a part of an automated CI/CD process, this code will remain vulnerable until fixed manually!

On Unix-Like systems, the system temporary directory is shared between all local users. When files/directories are created, the default umask settings for the process are respected. As a result, by default, most processes/apis will create files/directories with the permissions -rw-r--r-- and drwxr-xr-x respectively, unless an API that explicitly sets safe file permissions is used.

This vulnerability exists due to the use of the JDK method File.createTempFile. This method creates an insecure temporary files that can leave application and system data vulnerable to exposure.

Auto-generated code (Java, Scala) that deals with uploading or downloading binary data through API endpoints will create insecure temporary files during the process. For example, if the API endpoint returns a PDF file, the auto-generated clients will first download the PDF into a insecure temporary file that can be read by anyone on the system.

Affected generators:

Patches

The issue has been patched by changing the generated code to use the JDK method Files.createTempFile and released in the v5.1.0 stable version.

This vulnerability has the same root cause as CVE-2021-21364 from the swagger-api/swagger-codegen project as this project and that one both share the same original source tree. https://github.com/swagger-api/swagger-codegen/security/advisories/GHSA-hpv8-9rq5-hq7w

For more information

If you have any questions or comments about this advisory:

Open an issue in OpenAPI Generator Github repo
Email us at [email protected]

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.openapitools:openapi-generator`	all versions	5.1.0`org.openapitools:openapi-generator:5.1.0`

Affected Products

1 product · 1 configurations

Application

openapi generatoropenapi-generator

< 5.1.1

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

OpenAPI Generator allows generation of API client libraries (SDK generat…

github.comNVDMay 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.openapitools:openapi-generator, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.openapitools:openapi-generator to 5.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21430 is resolved across your whole dependency graph.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.

Frequently Asked Questions

### Impact **This vulnerability impacts generated code.** If this code was generated as a one-off occasion, not as a part of an automated CI/CD process, this code will remain vulnerable until fixed manually! On Unix-Like systems, the system temporary directory is shared between all local users. When files/directories are created, the default `umask` settings for the process are respected. As a result, by default, most processes/apis will create files/directories with the permissions `-rw-r--r--` and `drwxr-xr-x` respectively, unless an API that explicitly sets safe file permissions is used.

O3 Security · Impact-Aware SCA

Is CVE-2021-21430 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

5.5/10CVSS v3 base

Vector breakdown

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Raw vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CWE Classification

CWE-269Improper Privilege Management CWE-668CWE-668

Weaponization

No known public exploit tooling found.

OpenSSF Scorecard

Package health score

openapi-generator

4.0/10

Maintained10/10

Code-Review8/10

Branch-ProtectionN/A

Assessed Oct 19, 2026

Timeline

Disclosed

May 10, 2021

First exploit

May 19, 2021

Last updated

Oct 20, 2026

Identifiers

CVE-2021-21430

GHSA-cqxr-xf2w-943w

References

Advisorynvd.nist.gov Fixgithub.com Fixgithub.com Webgithub.com Packagegithub.com Evidencegithub.com

Related vulnerabilities

Also affects openapi-generator

This CVE is medium severity; 1 of 1 other CVE affecting openapi-generator is rated as high or higher (top: high).

CVE-2019-11405

Same weakness: CWE-269

This CVE is medium severity; 7 of 7 other CVEs with CWE-269 are rated as high or higher (top: critical).

CVE-2026-96627CVE-2026-85990CVE-2026-77524CVE-2026-95837GHSA-pjr3-86v4-5p7wCVE-2026-57458CVE-2026-105678Browse all CWE-269

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026

CVE-2021-21430 — openapi-generator

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Impact

Patches

For more information

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2021-21430 in your dependencies?