CVE-2021-21430: Generated Java and Scala Code Contains Local Information Disclosure Vulnerability

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)

    if (tempFolderPath == null)

    return File.createTempFile(prefix, suffix);

    else

    return File.createTempFile(prefix, suffix, new File(tempFolderPath));

  • jersey2

    if (tempFolderPath == null)

    return File.createTempFile(prefix, suffix);

    else

    return File.createTempFile(prefix, suffix, new File(tempFolderPath));

  • resteasy

    if (tempFolderPath == null)

    return File.createTempFile(prefix, suffix);

    else

    return File.createTempFile(prefix, suffix, new File(tempFolderPath));

  • retrofit2

    @Override

    public File convert(ResponseBody value) throws IOException {

    File file = File.createTempFile("retrofit-file", “.tmp”);

    Files.write(Paths.get(file.getPath()), value.bytes());

    return file;

    }

• Scala

  • scala-finch

    private def bytesToFile(input: Array[Byte]): java.io.File = {

    val file = File.createTempFile("tmp{{classname}}", null)

    val output = new FileOutputStream(file)

    output.write(input)

    file

    }

  • scala-akka

    val tempFileFromFileInfo: FileInfo => File = {

    file: FileInfo => File.createTempFile(file.fileName, “.tmp”)

    }

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.

References

#8787
#8791
#9348

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.
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]