Dir.open, Dir.new, Dir.entries and Dir.empty? accept the path of the target directory as their parameter. If the parameter contains NUL (\0) bytes, these methods recognize that the path is completed before the NUL bytes. So, if a script accepts an external input as the argument of these methods, the attacker can make the unintentional directory traversal.
Affected versions:
Ruby 2.2 series: 2.2.9 and earlier Ruby 2.3 series: 2.3.6 and earlier Ruby 2.4 series: 2.4.3 and earlier Ruby 2.5 series: 2.5.0 and earlier
External References:
https://www.ruby-lang.org/en/news/2018/03/28/poisoned-nul-byte-dir-cve-2018-8780/
In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, the UNIXServer.open and UNIXSocket.open methods are not checked for null characters. It may be connected to an unintended socket.
If an attacker sends a large request which contains huge HTTP headers, WEBrick try to process it on memory, so the request causes the out-of-memory DoS attack.
Affected versions:
Ruby 2.2 series: 2.2.9 and earlier Ruby 2.3 series: 2.3.6 and earlier Ruby 2.4 series: 2.4.3 and earlier Ruby 2.5 series: 2.5.0 and earlier
External References:
https://www.ruby-lang.org/en/news/2018/03/28/large-request-dos-in-webrick-cve-2018-8777/
In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, an attacker controlling the unpacking format (similar to format string vulnerabilities) can trigger a buffer under-read in the String#unpack method, resulting in a massive and controlled information disclosure.
Dir.mktmpdir method introduced by tmpdir library accepts the prefix and the suffix of the directory which is created as the first parameter. The prefix can contain relative directory specifiers "../", so this method can be used to target any directory. So, if a script accepts an external input as the prefix, and the targeted directory has inappropriate permissions or the ruby process has inappropriate privileges, the attacker can create a directory or a file at any directory.
Affected versions:
Ruby 2.2 series: 2.2.9 and earlier Ruby 2.3 series: 2.3.6 and earlier Ruby 2.4 series: 2.4.3 and earlier Ruby 2.5 series: 2.5.0 and earlier
External References:
https://www.ruby-lang.org/en/news/2018/03/28/unintentional-file-and-directory-creation-with-directory-traversal-cve-2018-6914/
An instance of OpenSSL::X509::Name contains entities such as CN, C and so on. Some two instances of OpenSSL::X509::Name are equal only when all entities are exactly equal. However, there is a bug that the equality check is not correct if the value of an entity of the argument (right-hand side) starts with the value of the receiver (left-hand side). So, if a malicious X.509 certificate is passed to compare with an existing certificate, there is a possibility to be judged incorrectly that they are equal.
External References:
https://www.ruby-lang.org/en/news/2018/10/17/openssl-x509-name-equality-check-does-not-work-correctly-cve-2018-16395/
An issue was discovered in Ruby before 2.3.8, 2.4.x before 2.4.5, 2.5.x before 2.5.2, and 2.6.x before 2.6.0-preview3. It does not taint strings that result from unpacking tainted strings with some formats.
If a script accepts an external input and outputs it without modification as a part of HTTP responses, an attacker can use newline characters to deceive the clients that the HTTP response header is stopped at there, and can inject fake HTTP responses after the newline characters to show malicious contents to the clients.
Affected versions:
Ruby 2.2 series: 2.2.9 and earlier Ruby 2.3 series: 2.3.6 and earlier Ruby 2.4 series: 2.4.3 and earlier Ruby 2.5 series: 2.5.0 and earlier
External References:
https://www.ruby-lang.org/en/news/2018/03/28/http-response-splitting-in-webrick-cve-2017-17742/