Trix is a what-you-see-is-what-you-get rich text editor for everyday writing. Versions prior to 2.1.12 are vulnerable to cross-site scripting when pasting malicious code in the link field. An attacker could trick the user to copy&paste a malicious `javascript:` URL as a link that would execute arbitrary JavaScript code within the context of the user's session, potentially leading to unauthorized actions being performed or sensitive information being disclosed. Users should upgrade to Trix editor version 2.1.12 or later to receive a patch. In addition to upgrading, affected users can disallow browsers that don't support a Content Security Policy (CSP) as a workaround for this and other cross-site scripting vulnerabilities. Set CSP policies such as script-src 'self' to ensure that only scripts hosted on the same origin are executed, and explicitly prohibit inline scripts using script-src-elem.
https://github.com/basecamp/trix/security/advisories/GHSA-j386-3444-qgwg
https://github.com/basecamp/trix/commit/c4f0d6f80654603932af6685694f694e96593b93
https://github.com/basecamp/trix/commit/180c8d337f18e1569cea6ef29b4d03ffff5b5faa
https://gist.github.com/th4s1s/3921fd9c3e324ad9a3e0d846166e3eb8