Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability. This update upgrades Firefox to version 91.9.0 ESR. Security Fix: * Mozilla: Bypassing permission prompt in nested browsing contexts * Mozilla: iframe Sandbox bypass * Mozilla: Fullscreen notification bypass using popups * Mozilla: Leaking browser history with CSS variables * Mozilla: Memory safety bugs fixed in Firefox 100 and Firefox ESR 91.9 * Mozilla: Reader mode bypassed SameSite cookies For more details about the security issue, including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page listed in the References section.