Package Instance

Sinatra vulnerable to Reliance on Untrusted Inputs in a Security Decision
Versions of the package sinatra from 0.0.0 are vulnerable to
Reliance on Untrusted Inputs in a Security Decision via the
X-Forwarded-Host (XFH) header.

When making a request to a method with redirect applied, it is
possible to trigger an Open Redirect Attack by inserting an
arbitrary address into this header. If used for caching purposes,
such as with servers like Nginx, or as a reverse proxy, without
handling the X-Forwarded-Host header, attackers can potentially
exploit Cache Poisoning or Routing-based SSRF.

sinatra does not validate expanded path matches
Sinatra before 2.2.0 does not validate that the expanded path matches public_dir when serving static files.

Sinatra vulnerable to Reflected File Download attack
An issue was discovered in Sinatra 2.0 before 2.2.3 and 3.0 before 3.0.4.
An application is vulnerable to a reflected file download (RFD) attack that
sets the Content-Disposition header of a response when the filename is
derived from user-supplied input.

Sinatra is vulnerable to ReDoS through ETag header value generation
There is a denial of service vulnerability in the `If-Match` and `If-None-Match` header parsing component of Sinatra, if the `etag` method is used when constructing the response and you are using Ruby < 3.2.

Cross-site Scripting
Sinatra has XSS via the Bad Request page that occurs upon a params parser exception.