It was found in vanilla forums before 2.0.10 a cross-site scripting vulnerability where a filename could contain arbitrary code to execute on the client side.
In Vanilla before 2.6.4, a flaw exists within the getSingleIndex function of the AddonManager class. The issue results in a require call using a crafted type value, leading to Directory Traversal with File Inclusion. An attacker can leverage this vulnerability to execute code under the context of the web server.
Vanilla before 2.5.5 and 2.6.x before 2.6.2 allows Remote Code Execution because authenticated administrators have a reachable call to unserialize in the Gdn_Format class.