Potential RCE with a compromised security key in craft/cms

Vulnerability Description

Craft is a flexible, user-friendly CMS for creating custom digital experiences on the web and beyond. This is an remote code execution (RCE) vulnerability that affects Craft 4 and 5 installs where your security key has already been compromised. Anyone running an unpatched version of Craft with a compromised security key is affected. This vulnerability has been patched in Craft 5.5.8 and 4.13.8. Users who cannot update to a patched version, should rotate their security keys and ensure their privacy to help migitgate the issue.

References

• https://github.com/craftcms/cms/security/advisories/GHSA-x684-96hh-833x
• https://github.com/craftcms/cms/commit/e59e22b30c9dd39e5e2c7fe02c147bcbd004e603
• https://craftcms.com/knowledge-base/securing-craft#keep-your-secrets-secret