This update for MozillaFirefox fixes the following issues: MozillaFirefox was updated to Extended Support Release 91.3.0 ESR * Fixed: Various stability, functionality, and security fixes MFSA 2021-49 * CVE-2021-38503: iframe sandbox rules did not apply to XSLT stylesheets * CVE-2021-38504: Use-after-free in file picker dialog * CVE-2021-38505: Windows 10 Cloud Clipboard may have recorded sensitive user data * CVE-2021-38506: Firefox could be coaxed into going into fullscreen mode without notification or warning * CVE-2021-38507: Opportunistic Encryption in HTTP2 could be used to bypass the Same-Origin-Policy on services hosted on other ports * CVE-2021-38508: Permission Prompt could be overlaid, resulting in user confusion and potential spoofing * CVE-2021-38509: Javascript alert box could have been spoofed onto an arbitrary domain * CVE-2021-38510: Download Protections were bypassed by .inetloc files on Mac OS * MOZ-2021-0008: Use-after-free in HTTP2 Session object * MOZ-2021-0007: Memory safety bugs fixed in Firefox 94 and Firefox ESR 91.3