MODX Revolution 2.x before 2.2.15 allows remote attackers to bypass the cross-site request forgery (CSRF) protection mechanism by (1) omitting the CSRF token or via a (2) long string in the CSRF token parameter.
The (1) update and (2) package-installation features in MODX Revolution 2.5.4-pl and earlier do not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and trigger the execution of arbitrary code via a crafted certificate.