CVE-2021-21364

swagger-codegen is an open-source project which contains a template-driven engine to generate documentation, API clients and server stubs in different languages by parsing your OpenAPI / Swagger definition. In swagger-codegen before version 2.4.19, 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. Because this vulnerability impacts generated code, the generated code will remain vulnerable until fixed manually! This vulnerability is fixed in version 2.4.19. Note this is a distinct vulnerability from CVE-2021-21363.

swagger-codegen is an open-source project which contains a template-driven engine to generate documentation, API clients and server stubs in different languages by parsing your OpenAPI / Swagger definition. In swagger-codegen before version 2.4.19, 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. Because this vulnerability impacts generated code, the generated code will remain vulnerable until fixed manually! This vulnerability is fixed in version 2.4.19. Note this is a distinct vulnerability from CVE-2021-21363.

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.

Java Code

The method File.createTempFile from the JDK is vulnerable to this local information disclosure vulnerability.

• https://github.com/swagger-api/swagger-codegen/blob/068b1ebcb7b04a48ad38f1cadd24bb3810c9f1ab/modules/swagger-codegen/src/main/resources/kotlin-client/infrastructure/ApiClient.kt.mustache#L209
• https://github.com/swagger-api/swagger-codegen/blob/068b1ebcb7b04a48ad38f1cadd24bb3810c9f1ab/modules/swagger-codegen/src/main/resources/finch/api.mustache#L84
• https://github.com/swagger-api/swagger-codegen/blob/068b1ebcb7b04a48ad38f1cadd24bb3810c9f1ab/modules/swagger-codegen/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache#L831-L834
• https://github.com/swagger-api/swagger-codegen/blob/068b1ebcb7b04a48ad38f1cadd24bb3810c9f1ab/modules/swagger-codegen/src/main/resources/Java/libraries/jersey2/ApiClient.mustache#L630-L633

Patches

Fix has been applied to the master branch with:

• https://github.com/swagger-api/swagger-codegen/commit/35adbd552d5f99b3ff1e0e59da228becc85190f2

included in release: 2.4.19

Workarounds

Users can remediate the vulnerability in non patched version by manually (or programmatically e.g. in CI) updating the generated source code to use java.nio.files.Files temporary file creation instead of java.io.File, e.g. by changing

    if (tempFolderPath == null)
      return File.createTempFile(prefix, suffix);
    else
      return File.createTempFile(prefix, suffix, new File(tempFolderPath));

to

    if (tempFolderPath == null)
      return Files.createTempFile(prefix, suffix).toFile();
    else
      return Files.createTempFile(Paths.get(tempFolderPath), prefix, suffix).toFile();

or generally changing:

File.createTempFile(prefix, suffix);

to

Files.createTempFile(prefix, suffix).toFile();

References

• CWE-378: Creation of Temporary File With Insecure Permissions
• CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
• CWE-732: Incorrect Permission Assignment for Critical Resource

For more information

If you have any questions or comments about this advisory:

• Email us at [email protected]

Original vulnerability report

I'm performing OSS security research under the GitHub Security Lab Bug Bounty program. I've been using a custom CodeQL query to find local temporary directory vulnerabilities in OSS with three custom CodeQL queries.

• https://github.com/github/codeql/pull/4388/files#diff-71d36c0f2bd0b08e32866f873f1c906cdc17277e0ad327c0c6cd2c882f30de4f
• https://github.com/github/codeql/pull/4388/files#diff-1893a18a8bf43c011d61a7889d0139b998a5a78701a30fe7722eddd4c506aaac
• https://github.com/github/codeql/pull/4473

The code generated by the Swagger Generator contains a local information disclosure vulnerability. The system temporary directory, on unix-like systems is shared between multiple users. Information written to this directory, or directories created under this directory that do not correctly set the posix standard permissions can have these directories read/modified by other users.

---

This code exists in the code generator, in the generated code.

In this…

swagger-codegen is an open-source project which contains a template-driven engine to generate documentation, API clients and server stubs in different languages by parsing your OpenAPI / Swagger definition. In swagger-codegen before version 2.4.19, 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. Because this vulnerability impacts generated code, the generated code will remain vulnerable until fixed manually! This vulnerability is fixed in version 2.4.19. Note this is a distinct vulnerability from CVE-2021-21363.

swagger-codegen is an open-source project which contains a template-driven engine to generate documentation, API clients and server stubs in different languages by parsing your OpenAPI / Swagger definition. In swagger-codegen before version 2.4.19, 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. Because this vulnerability impacts generated code, the generated code will remain vulnerable until fixed manually! This vulnerability is fixed in version 2.4.19. Note this is a distinct vulnerability from CVE-2021-21363.

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.

Java Code

The method File.createTempFile from the JDK is vulnerable to this local information disclosure vulnerability.

• https://github.com/swagger-api/swagger-codegen/blob/068b1ebcb7b04a48ad38f1cadd24bb3810c9f1ab/modules/swagger-codegen/src/main/resources/kotlin-client/infrastructure/ApiClient.kt.mustache#L209
• https://github.com/swagger-api/swagger-codegen/blob/068b1ebcb7b04a48ad38f1cadd24bb3810c9f1ab/modules/swagger-codegen/src/main/resources/finch/api.mustache#L84
• https://github.com/swagger-api/swagger-codegen/blob/068b1ebcb7b04a48ad38f1cadd24bb3810c9f1ab/modules/swagger-codegen/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache#L831-L834
• https://github.com/swagger-api/swagger-codegen/blob/068b1ebcb7b04a48ad38f1cadd24bb3810c9f1ab/modules/swagger-codegen/src/main/resources/Java/libraries/jersey2/ApiClient.mustache#L630-L633

Patches

Fix has been applied to the master branch with:

• https://github.com/swagger-api/swagger-codegen/commit/35adbd552d5f99b3ff1e0e59da228becc85190f2

included in release: 2.4.19

Workarounds

Users can remediate the vulnerability in non patched version by manually (or programmatically e.g. in CI) updating the generated source code to use java.nio.files.Files temporary file creation instead of java.io.File, e.g. by changing

    if (tempFolderPath == null)
      return File.createTempFile(prefix, suffix);
    else
      return File.createTempFile(prefix, suffix, new File(tempFolderPath));

to

    if (tempFolderPath == null)
      return Files.createTempFile(prefix, suffix).toFile();
    else
      return Files.createTempFile(Paths.get(tempFolderPath), prefix, suffix).toFile();

or generally changing:

File.createTempFile(prefix, suffix);

to

Files.createTempFile(prefix, suffix).toFile();

References

• CWE-378: Creation of Temporary File With Insecure Permissions
• CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
• CWE-732: Incorrect Permission Assignment for Critical Resource

For more information

If you have any questions or comments about this advisory:

• Email us at [email protected]

Original vulnerability report

I'm performing OSS security research under the GitHub Security Lab Bug Bounty program. I've been using a custom CodeQL query to find local temporary directory vulnerabilities in OSS with three custom CodeQL queries.

• https://github.com/github/codeql/pull/4388/files#diff-71d36c0f2bd0b08e32866f873f1c906cdc17277e0ad327c0c6cd2c882f30de4f
• https://github.com/github/codeql/pull/4388/files#diff-1893a18a8bf43c011d61a7889d0139b998a5a78701a30fe7722eddd4c506aaac
• https://github.com/github/codeql/pull/4473

The code generated by the Swagger Generator contains a local information disclosure vulnerability. The system temporary directory, on unix-like systems is shared between multiple users. Information written to this directory, or directories created under this directory that do not correctly set the posix standard permissions can have these directories read/modified by other users.

---

This code exists in the code generator, in the generated code.

In this…