Privileged content access and execution via XBL — Mozilla

Security researcher Mariusz Mlynski reported that it is possible to compile a user-defined function in the XBL scope of a specific element and then trigger an event within this scope to run code. In some circumstances, when this code is run, it can access content protected by System Only Wrappers (SOW) and chrome-privileged pages. This could potentially lead to arbitrary code execution. Additionally, Chrome Object Wrappers (COW) can be bypassed by web content to access privileged methods, leading to a cross-site scripting (XSS) attack from privileged pages.