A blind Server-Side Request Forgery (SSRF) vulnerability was found in Moodle. This flaw exists due to insufficient validation of user-supplied input in LTI provider library. The library does not utilise Moodle's inbuilt cURL helper, which resulted in a blind SSRF risk. An attacker can send a specially crafted HTTP request and trick the application to initiate requests to arbitrary systems. This vulnerability allows a remote attacker to perform SSRF attacks.
https://moodle.org/mod/forum/discuss.php?d=440772
https://bugzilla.redhat.com/show_bug.cgi?id=2142775
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-71920