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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. 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

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:

References