mechanize, a library for automatically interacting with HTTP web servers, contains a regular expression that is vulnerable to regular expression denial of service (ReDoS) prior to version 0.4.6. If a web server responds in a malicious way, then mechanize could crash. Version 0.4.6 has a patch for the issue.
The Mechanize library is used for automating interaction with websites. Mechanize automatically stores and sends cookies, follows redirects, and can follow links and submit forms. In versions prior to 2.8.5 the Authorization header is leaked after a redirect to a different port on the same site. Users are advised to upgrade to Mechanize v2.8.5 or later. There are no known workarounds for this issue.
Mechanize is an open-source ruby library that makes automated web interaction easy.