Medium · published August 31, 2026
Stored Cross-Site Scripting (XSS) in TaskRunHandler.post() in web/handlers/task.py in QD 20220208 through 20250803. When a task is run via /task/<taskid>/run, the handler renders task log content (logtmp) into the HTML response using Python % string formatting without HTML encoding. logtmp is populated from the exception object or from new_env.variables.__log__, which is attacker-controlled via the template extract_variables mechanism. A low-privileged authenticated attacker can create a crafted HAR template that extracts arbitrary HTML/JavaScript into the __log__ variable via the api://util/unicode endpoint. When a victim triggers the task run, the embedded script executes in the victim browser within the QD application context.