Improper escaping of encrypted topic titles can lead to Cross-site Scripting under non-default site configuration

Vulnerability Description

discourse-encrypt is a plugin that provides a secure communication channel through Discourse. Improper escaping of encrypted topic titles could lead to a cross site scripting (XSS) issue when a site has content security policy (CSP) headers disabled. Having CSP disabled is a non-default configuration, and having it disabled with discourse-encrypt installed will result in a warning in the Discourse admin dashboard. This has been fixed in commit `9c75810af9` which is included in the latest version of the discourse-encrypt plugin. Users are advised to upgrade. Users unable to upgrade should ensure that CSP headers are enabled and properly configured.

References

• https://github.com/discourse/discourse-encrypt/security/advisories/GHSA-5fh6-wp7p-xx7v
• https://github.com/discourse/discourse-encrypt/commit/9c75810af9a474d7edaec67dea66f852c0ba1f4e
• https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP