In RESTEasy the insecure File.createTempFile() is used in the DataSourceProvider, FileProvider and Mime4JWorkaround classes which creates temp files with insecure permissions that could be read by a local user.

A reflected Cross-Site Scripting (XSS) flaw was found in RESTEasy in all versions of RESTEasy up to 4.6.0.Final, where it did not properly handle URL encoding when calling @javax.ws.rs.PathParam without any @Produces MediaType. This flaw allows an attacker to launch a reflected XSS attack. The highest threat from this vulnerability is to data confidentiality and integrity.

A vulnerability was found in RESTEasy, where RootNode incorrectly caches routes. This issue results in hash flooding, leading to slower requests with higher CPU time spent searching and adding the entry. This flaw allows an attacker to cause a denial of service.

A flaw was found in RESTEasy in all versions of RESTEasy up to 4.6.0.Final. The endpoint class and method names are returned as part of the exception response when RESTEasy cannot convert one of the request URI path or query values to the matching JAX-RS resource method's parameter value. The highest threat from this vulnerability is to data confidentiality.

A flaw was found in all resteasy 3.x.x versions prior to 3.12.0.Final and all resteasy 4.x.x versions prior to 4.6.0.Final, where an improper input validation results in returning an illegal header that integrates into the server's response. This flaw may result in an injection, which leads to unexpected behavior when the HTTP response is constructed.