An issue was discovered in Ruby through 2.5.8, 2.6.x through 2.6.6, and 2.7.x through 2.7.1. WEBrick, a simple HTTP server bundled with Ruby, had not checked the transfer-encoding header value rigorously. An attacker may potentially exploit this issue to bypass a reverse proxy (which also has a poor header check), which may lead to an HTTP Request Smuggling attack.
In Puma (RubyGem) before 4.3.2 and before 3.12.3, if an application using Puma allows untrusted input in a response header, an attacker can use newline characters (i.e. `CR`, `LF` or`/r`, `/n`) to end the header and inject malicious content, such as additional headers or an entirely new response body. This vulnerability is known as HTTP Response Splitting. While not an attack in itself, response splitting is a vector for several other attacks, such as cross-site scripting (XSS). This is related to CVE-2019-16254, which fixed this vulnerability for the WEBrick Ruby web server. This has been fixed in versions 4.3.2 and 3.12.3 by checking all headers for line endings and rejecting headers with those characters.
Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 allows HTTP Response Splitting. If a program using WEBrick inserts untrusted input into the response header, an attacker can exploit it to insert a newline character to split a header, and inject malicious content to deceive clients. NOTE: this issue exists because of an incomplete fix for CVE-2017-17742, which addressed the CRLF vector, but did not address an isolated CR or an isolated LF.
Directory traversal vulnerability in controller/concerns/render_redirect.rb in the Wicked gem before 1.0.1 for Ruby allows remote attackers to read arbitrary files via a %2E%2E%2F (encoded dot dot slash) in the step.
Phusion Passenger gem before 3.0.21 and 4.0.x before 4.0.5 for Ruby allows local users to cause a denial of service (prevent application start) or gain privileges by pre-creating a temporary "config" file in a directory with a predictable name in /tmp/ before it is used by the gem.
ext/common/ServerInstanceDir.h in Phusion Passenger gem before 4.0.6 for Ruby allows local users to gain privileges or possibly change the ownership of arbitrary directories via a symlink attack on a directory with a predictable name in /tmp/.
multi_xml gem 0.5.2 for Ruby, as used in Grape before 0.2.6 and possibly other products, does not properly restrict casts of string values, which allows remote attackers to conduct object-injection attacks and execute arbitrary code, or cause a denial of service (memory and CPU consumption) involving nested XML entity references, by leveraging support for (1) YAML type conversion or (2) Symbol type conversion, a similar vulnerability to CVE-2013-0156.
Devise gem 2.2.x before 2.2.3, 2.1.x before 2.1.3, 2.0.x before 2.0.5, and 1.5.x before 1.5.4 for Ruby, when using certain databases, does not properly perform type conversion when performing database queries, which might allow remote attackers to cause incorrect results to be returned and bypass security checks via unknown vectors, as demonstrated by resetting passwords of arbitrary accounts.
The extract_from_ocr function in lib/docsplit/text_extractor.rb in the Karteek Docsplit (karteek-docsplit) gem 0.5.4 for Ruby allows context-dependent attackers to execute arbitrary commands via shell metacharacters in a PDF filename.