Chrome privilege escalation in XPCVariant::VariantDataToJS() — Mozilla

Mozilla security researcher moz_bug_r_a4 reported that the XPCOM utility XPCVariant::VariantDataToJS unwrapped doubly-wrapped objects before returning them to chrome callers. This could result in chrome privileged code calling methods on an object which had previously been created or modified by web content, potentially executing malicious JavaScript code with chrome privileges.