The open-uri-cached rubygem allows local users to execute arbitrary Ruby code by creating a directory under /tmp containing "openuri-" followed by a crafted UID, and putting Ruby code in said directory once a metafile is created.

References

• https://nvd.nist.gov/vuln/detail/CVE-2015-3649
• http://www.benjaminfleischer.com/2013/03/20/yaml-and-security-in-ruby/
• http://www.openwall.com/lists/oss-security/2015/05/06/2
• tigris/open-uri-cached#8
• https://github.com/rubysec/ruby-advisory-db/blob/master/gems/open-uri-cached/CVE-2015-3649.yml
• http://seclists.org/oss-sec/2015/q2/373
• https://github.com/tigris/open-uri-cached/blob/master/lib/open-uri/cached.rb
• https://web.archive.org/web/20210119122105/http://www.securityfocus.com/bid/74469