Mechanize is a Ruby library used for automating interaction with websites.
Mechanize does not neutralize filename input and could allow arbitrary code execution if an attacker can control filenames used by Mechanize.
Please review the referenced CVE identifiers for details.
There is no known workaround at this time.
All Mechanize users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-ruby/mechanize-2.7.7"