Headline
GHSA-x684-96hh-833x: Craft CMS has a potential RCE with a compromised security key
Impact
This is an RCE vulnerability that affects Craft 4 and 5 installs where your security key has already been compromised.
https://craftcms.com/knowledge-base/securing-craft#keep-your-secrets-secret
Anyone running an unpatched version of Craft with a compromised security key is affected.
Patches
This has been patched in Craft 5.5.8 and 4.13.8.
Workarounds
If you can’t update to a patched version, then rotating your security key and ensuring its privacy will help to migitgate the issue.
References
https://github.com/craftcms/cms/commit/e59e22b30c9dd39e5e2c7fe02c147bcbd004e603
Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.