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 cross-site scripting (XSS) flaw was found in RESTEasy in versions before 3.11.1.Final and before 4.5.3.Final, where it did not properly handle URL encoding when the RESTEASY003870 exception occurs. An attacker could use this flaw to launch a reflected XSS attack.

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 RESTEasy client in all versions of RESTEasy up to 4.5.6.Final. It may allow client users to obtain the server's potentially sensitive information when the server got WebApplicationException from the RESTEasy client call. The highest threat from this vulnerability is to data confidentiality.

JBoss RESTEasy before version 3.1.2 could be forced into parsing a request with YamlProvider, resulting in unmarshalling of potentially untrusted data which could allow an attacker to execute arbitrary code with RESTEasy application permissions.

RESTEasy before 2.3.1 allows remote attackers to read arbitrary files via an external entity reference in a DOM document, aka an XML external entity (XXE) injection attack.

The readFrom function in providers.jaxb.JAXBXmlTypeProvider in RESTEasy before 2.3.2 allows remote attackers to read arbitrary files via an external entity reference in a Java Architecture for XML Binding (JAXB) input, aka an XML external entity (XXE) injection attack, a similar vulnerability to CVE-2012-0818.