Trix allows Cross-site Scripting via `javascript:` url in a link

The Trix editor, versions prior to 2.1.11, is vulnerable to XSS when pasting malicious code in the link field.

Impact

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.

See https://gist.github.com/th4s1s/3921fd9c3e324ad9a3e0d846166e3eb8

Patches

Update Recommendation: Users should upgrade to Trix editor version 2.1.12 or later.

Workarounds

This is not really a workaround but something that should be considered in addition to upgrading to the patched version. If affected users can disallow browsers that don't support a Content Security Policy, then this would be an effective workaround for this and all XSS 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.

References

https://gist.github.com/th4s1s/3921fd9c3e324ad9a3e0d846166e3eb8

Credits

This vulnerability was reported by Hackerone researcher https://hackerone.com/lio346?type=user