Discourse vulnerable to DoS via Regexp Injection in Full Name

Vulnerability Description

Discourse is an open source platform for community discussion. Prior to version 3.1.3 of the `stable` branch and version 3.2.0.beta3 of the `beta` and `tests-passed` branches, if a user has been quoted and uses a `|` in their full name, they might be able to trigger a bug that generates a lot of duplicate content in all the posts they've been quoted by updating their full name again. Version 3.1.3 of the `stable` branch and version 3.2.0.beta3 of the `beta` and `tests-passed` branches contain a patch for this issue. No known workaround exists, although one can stop the "bleeding" by ensuring users only use alphanumeric characters in their full name field.

References

• https://github.com/discourse/discourse/security/advisories/GHSA-hcgf-hg2g-mw78
• https://github.com/discourse/discourse/commit/2ec25105179199cf80912bf011c18b8b870e1863
• https://github.com/discourse/discourse/commit/7d484864fe91ff79c478f57e7ddb1235d701921e