RLSA-2021:4123

Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability.

This update upgrades Firefox to version 91.3.0 ESR.

Security Fix(es):

• Mozilla: Use-after-free in HTTP2 Session object

• Mozilla: Memory safety bugs fixed in Firefox 94 and Firefox ESR 91.3

• Mozilla: iframe sandbox rules did not apply to XSLT stylesheets (CVE-2021-38503)

• Mozilla: Use-after-free in file picker dialog (CVE-2021-38504)

• Mozilla: Firefox could be coaxed into going into fullscreen mode without notification or warning (CVE-2021-38506)

• Mozilla: Opportunistic Encryption in HTTP2 could be used to bypass the Same-Origin-Policy on services hosted on other ports (CVE-2021-38507)

• Mozilla: Permission Prompt could be overlaid, resulting in user confusion and potential spoofing (CVE-2021-38508)

• Mozilla: Javascript alert box could have been spoofed onto an arbitrary domain (CVE-2021-38509)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.