A reflected cross-site scripting vulnerability in the invocation-tag generation interface of Revive Adserver 6.0.8 and earlier allows an unauthenticated attacker to execute JavaScript in an authenticated user's browser by persuading them to visit a crafted URL. When Direct Selection is enabled, an attacker-controlled banner identifier can be included in HTML form fields without appropriate encoding. Direct Selection is disabled by default. The issue is fixed in Revive Adserver 6.0.9 by HTML-encoding banner identifier values in the invocation-option form fields.