CVE-2021-21430
Creation of Temporary File in Directory with Insecure Permissions in auto-generated Java, Scala code
OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec. Using File.createTempFile in JDK will result in creating and using insecure temporary files that can leave application and system data vulnerable to attacks. Auto-generated code (Java, Scala) that deals with uploading or downloading binary data through API endpoints will create insecure temporary files during the process. Affected generators: java (jersey2, okhttp-gson (default library)), scala-finch. The issue has been patched with Files.createTempFile and released in the v5.1.0 stable version.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Creation of Temporary File in Directory with Insecure Permissions in auto-generated Java, Scala code
OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec. Using File.createTempFile in JDK will result in creating and using insecure temporary files that can leave application and system data vulnerable to attacks. Auto-generated code (Java, Scala) that deals with uploading or downloading binary data through API endpoints will create insecure temporary files during the process. Affected generators: java (jersey2, okhttp-gson (default library)), scala-finch. The issue has been patched with Files.createTempFile and released in the v5.1.0 stable version.
- Record
CVE-2021-21430- CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-269
- Updated
- 2026-11-02
EUVDEUVD-2021-1049
OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec. Using File.createTempFile in JDK will result in creating and using insecure temporary files that can leave application and system data vulnerable to attacks. Auto-generated code (Java, Scala) that deals with uploading or downloading binary data through API endpoints will create insecure temporary files during the process. Affected generators: java (jersey2, okhttp-gson (default library)), scala-finch. The issue has been patched with Files.createTempFile and released in the v5.1.0 stable version.
- Record
EUVD-2021-1049- CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-cqxr-xf2w-943w
Creation of Temporary File in Directory with Insecure Permissions in auto-generated Java, Scala code
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:
- Java
okhttp-gson(default library) https://github.com/OpenAPITools/openapi-generator/blob/d85f61ff0cfd6b8cd7063a63f302998a51466269/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache#L1085-L1088jersey2https://github.com/OpenAPITools/openapi-generator/blob/d85f61ff0cfd6b8cd7063a63f302998a51466269/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache#L1035-L1038resteasyhttps://github.com/OpenAPITools/openapi-generator/blob/d85f61ff0cfd6b8cd7063a63f302998a51466269/modules/openapi-generator/src/main/resources/Java/libraries/resteasy/ApiClient.mustache#L604-L607retrofit2https://github.com/OpenAPITools/openapi-generator/blob/d85f61ff0cfd6b8cd7063a63f302998a51466269/modules/openapi-generator/src/main/resources/Java/libraries/retrofit2/play26/ApiClient.mustache#L202-L208
- Scala
scala-finchhttps://github.com/OpenAPITools/openapi-generator/blob/764a3b044c19fadf4a0789473cde96a65b77868a/modules/openapi-generator/src/main/resources/scala-finch/api.mustache#L83-L88scala-akkahttps://github.com/OpenAPITools/openapi-generator/blob/150e24dc553a8ea5230ffb938ed3e6020e972faa/modules/openapi-generator/src/main/resources/scala-akka-http-server/multipartDirectives.mustache#L71-L73
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]
- Record
GHSA-cqxr-xf2w-943w- CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-269, CWE-377, CWE-378, CWE-379, CWE-668
- Updated
- 2026-11-02
NVD
OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec. Using File.createTempFile in JDK will result in creating and using insecure temporary files that can leave application and system data vulnerable to attacks. Auto-generated code (Java, Scala) that deals with uploading or downloading binary data through API endpoints will create insecure temporary files during the process. Affected generators: java (jersey2, okhttp-gson (default library)), scala-finch. The issue has been patched with Files.createTempFile and released in the v5.1.0 stable version.
- Record
CVE-2021-21430- CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 2.1 Low
AV:L/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-269, CWE-668
- Updated
- 2026-11-02
OSV
OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec. Using File.createTempFile in JDK will result in creating and using insecure temporary files that can leave application and system data vulnerable to attacks. Auto-generated code (Java, Scala) that deals with uploading or downloading binary data through API endpoints will create insecure temporary files during the process. Affected generators: java (jersey2, okhttp-gson (default library)), scala-finch. The issue has been patched with Files.createTempFile and released in the v5.1.0 stable version.
- Record
CVE-2021-21430- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-cqxr-xf2w-943w
Creation of Temporary File in Directory with Insecure Permissions in auto-generated Java, Scala code
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:
- Java
okhttp-gson(default library) https://github.com/OpenAPITools/openapi-generator/blob/d85f61ff0cfd6b8cd7063a63f302998a51466269/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache#L1085-L1088jersey2https://github.com/OpenAPITools/openapi-generator/blob/d85f61ff0cfd6b8cd7063a63f302998a51466269/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache#L1035-L1038resteasyhttps://github.com/OpenAPITools/openapi-generator/blob/d85f61ff0cfd6b8cd7063a63f302998a51466269/modules/openapi-generator/src/main/resources/Java/libraries/resteasy/ApiClient.mustache#L604-L607retrofit2https://github.com/OpenAPITools/openapi-generator/blob/d85f61ff0cfd6b8cd7063a63f302998a51466269/modules/openapi-generator/src/main/resources/Java/libraries/retrofit2/play26/ApiClient.mustache#L202-L208
- Scala
scala-finchhttps://github.com/OpenAPITools/openapi-generator/blob/764a3b044c19fadf4a0789473cde96a65b77868a/modules/openapi-generator/src/main/resources/scala-finch/api.mustache#L83-L88scala-akkahttps://github.com/OpenAPITools/openapi-generator/blob/150e24dc553a8ea5230ffb938ed3e6020e972faa/modules/openapi-generator/src/main/resources/scala-akka-http-server/multipartDirectives.mustache#L71-L73
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]
- Record
GHSA-cqxr-xf2w-943w- CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-269, CWE-377, CWE-378, CWE-379, CWE-668
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
org.openapitools:openapi-generatorMaven |
before 5.1.0 | 5.1.0 |
org.openapitools:openapi-generatorMaven |
before 5.1.0, plus listed versions 3.0.03.0.13.0.23.0.33.1.0 Show 33 moreShow less3.1.13.1.23.2.03.2.13.2.23.2.33.3.03.3.13.3.23.3.33.3.44.0.04.0.0-beta4.0.0-beta24.0.0-beta34.0.14.0.24.0.34.1.04.1.14.1.24.1.34.2.04.2.14.2.24.2.34.3.04.3.15.0.05.0.0-beta5.0.0-beta25.0.0-beta35.0.1 |
5.1.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21430 is a medium vulnerability (CVSS 6.2) in Openapi-generator Openapi Generator, published May 10, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.40%, the 34th percentile. Fixed in org.openapitools:openapi-generator 5.1.0.
References
github.com/OpenAPITools/openapi-generator/security/advisories/GHSA-cqxr-xf2w-943w
nvd.nist.gov/vuln/detail/CVE-2021-21430