YARD is a documentation generation tool for the Ruby programming language. Prior to version 0.9.44, YARD's static cache lookup reads a request path before the router's path cleanup runs. When a server is configured with a document root, a traversal path such as `/../yard-cache-secret.html` is joined against that root and can return a readable sibling `.html` file outside the intended static tree. Version 0.9.44 patches the issue.

YARD is a Ruby Documentation tool. Prior to version 0.9.42, a path traversal vulnerability was discovered in YARD when using yard server to serve documentation. This bug would allow unsanitized HTTP requests to access arbitrary files on the machine of a yard server host under certain conditions. This issue has been patched in version 0.9.42.

YARD is a Ruby Documentation tool. The "frames.html" file within the Yard Doc's generated documentation is vulnerable to Cross-Site Scripting (XSS) attacks due to inadequate sanitization of user input within the JavaScript segment of the "frames.erb" template file. This vulnerability is fixed in 0.9.36.

yard before 0.9.20 allows path traversal.

lib/yard/core_ext/file.rb in the server in YARD before 0.9.11 does not block relative paths with an initial ../ sequence, which allows attackers to conduct directory traversal attacks and read arbitrary files.