Under certain circumstances, a JavaScript alert (or prompt) could have been shown while another website was displayed underneath it. This could have been abused to…

Web-accessible extension pages (pages with a moz-extension:// scheme) were not correctly enforcing the frame-ancestors directive when it was used in the Web Extension’s Content Security…

When importing resources using Web Workers, error messages would distinguish the difference between <code>application/javascript</code> responses and non-script responses. This could have been abused to learn…

If a document created a sandboxed iframe without <code>allow-scripts</code>, and subsequently appended an element to the iframe’s document that e.g. had a JavaScript event handler…

When clicking on a tel: link, USSD codes, specified after a <code>*</code> character, would be included in the phone number. On certain phones, or on…

Remote Agent, used in WebDriver, did not validate the Host or Origin headers. This could have allowed websites to connect back locally to the user’s…

If a user was convinced to drag and drop an image to their desktop or other folder, the resulting object could have been changed into…

By using XSL Transforms, a malicious webserver could have served a user an XSL document that would continue to execute JavaScript (within the bounds of…

If a user installed an extension of a particular type, the extension could have auto-updated itself and while doing so, bypass the prompt which grants…

A Time-of-Check Time-of-Use bug existed in the Maintenance (Updater) Service that could be abused to grant Users write access to an arbitrary directory. This could…