Mojolicious versions from 0.999922 for Perl uses a hard coded string, or the application's class name, as an HMAC session cookie secret by default.
These predictable default secrets can be exploited by an attacker to forge session cookies. An attacker who knows or guesses the secret could compute valid HMAC signatures for the session cookie, allowing them to tamper with or hijack another user’s session.
Mojolicious versions from 7.28 for Perl will generate weak HMAC session cookie secrets via "mojo generate app" by default
When creating a default app skeleton with the "mojo generate app" tool, a weak secret is written to the application's configuration file using the insecure rand() function, and used for authenticating and protecting the integrity of the application's sessions. This may allow an attacker to brute force the application's session keys.
Cross-site scripting (XSS) vulnerability in the link_to helper in Mojolicious before 1.12 allows remote attackers to inject arbitrary web script or HTML via unspecified vectors.
Commands.pm in Mojolicious before 0.999928 does not properly perform CGI environment detection, which has unspecified impact and remote attack vectors.
Directory traversal vulnerability in Path.pm in Mojolicious before 1.16 allows remote attackers to read arbitrary files via a %2f..%2f (encoded slash dot dot slash) in a URI.