Skip to content
OpenAdvisories
High ALSA-2021:4123 6 CVEs

Important: firefox security update

Published Nov 3, 2021 · Updated Oct 29, 2026

Ecosystem: AlmaLinux

Summary

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.

Fixed packages 1

ReleasePackageFixed in
AlmaLinux · 8 firefox 91.3.0-1.el8_4.alma

Vulnerabilities 6

References

  • report
    https://vulners.com/cve/CVE-2021-38503
  • report
    https://vulners.com/cve/CVE-2021-38504
  • report
    https://vulners.com/cve/CVE-2021-38506
  • report
    https://vulners.com/cve/CVE-2021-38507
  • report
    https://vulners.com/cve/CVE-2021-38508
  • report
    https://vulners.com/cve/CVE-2021-38509