Arr-pm is an RPM reader/writer library written in Ruby. Versions prior to 0.0.12 are subject to OS command injection resulting in shell execution if the RPM contains a malicious "payload compressor" field. This vulnerability impacts the `extract` and `files` methods of the `RPM::File` class of this library. Version 0.0.12 patches these issues. A workaround for this issue is to ensure any RPMs being processed contain valid/known payload compressor values such as gzip, bzip2, xz, zstd, and lzma. The payload compressor field in an rpm can be checked by using the rpm command line tool.

Affected: RubyGems: arr-pm

### Impact

Arbitrary shell execution is possible when using RPM::File#files and RPM::File#extract if the RPM contains a malicious "payload compressor" field.

This vulnerability impacts the `extract` and `files` methods of the `RPM::File` class in the affected versions of this library.

### Patches

Version 0.0.12 is available with a fix for these issues.

### Workarounds

When using an affected version of this library (arr-pm), ensure any RPMs being processed contain valid/known payload compressor values. Such values include: gzip, bzip2, xz, zstd, and lzma.

You can check the payload compressor field in an rpm by using the rpm command line tool. For example:

``` % rpm -qp example-1.0-1.x86_64.rpm --qf "%{PAYLOADCOMPRESSOR}\n" gzip ```

### Impact on known dependent projects

This library is used by [fpm](https://github.com/jordansissel/fpm). The vulnerability may impact fpm only when using the flag `-s rpm` or `--input-type rpm` to convert a malicious rpm to another format. It does not impact creating rpms.

### References

* https://github.com/jordansissel/ruby-arr-pm/pull/14 * https://github.com/jordansissel/ruby-arr-pm/pull/15

### Credit

Thanks to @joernchen for reporting this problem and contributing to the resolution :)

### For more information

If you have any questions or comments about this advisory: * Open an issue in [the arr-pm issue tracker](https://github.com/jordansissel/ruby-arr-pm/)