Vulnerabilities

Mozilla developers Paul Adenot and the Mozilla Fuzzing Team reported memory safety bugs present in Firefox 96 and Firefox ESR 91.5.

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

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 Policy.

When importing resources using Web Workers, error messages would distinguish the difference between <code>application/javascript</code> responses and non-script responses.

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.

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

Remote Agent, used in WebDriver, did not validate the Host or Origin headers.

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 an executable script which would have run arbitrary code after the user clicked on it.

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 the same-origin policy) even after the tab was closed.

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 the new version the new requested permissions.

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.

Mozilla developers and community members Gabriele Svelto, Sebastian Hengst, Randell Jesup, Luan Herrera, Lars T Hansen, and the Mozilla Fuzzing Team reported memory safety bugs present in Firefox 96.