RAR and UnRAR provide command line interfaces for compressing and decompressing RAR files.
Due to an error in the validation of symbolic links within archives, RAR and UnRAR can potentially write files to a directory which is outside of the intended unpack directory.
If the user running RAR or UnRAR extracts a malicious archive, the archive could overwrite a file such as the user's shell initialization scripts, potentially resulting in arbitrary code execution in the context of that user.
There is no known workaround at this time.
All RAR users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-arch/rar-6.23"
All UnRAR users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-arch/unrar-6.2.10"