ISN 2026-22: Firefox ESR Vulnerabilities

First published 2 June 2026

CVSS:3.1: 7.3 (High)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Summary

Multiple security vulnerabilities have been found in Firefox ESR, a web browser used in IGEL OS. This affects the following product versions:

  • IGEL OS 12

  • IGEL OS 11

Details

Incorrect boundary conditions have been found in the JavaScript Engine (CVE-2026-8388, high) and the Web Codecs Firefox component (CVE-2026-8946, high). The JavaScript Engine also suffers from an improper input validation issue (CVE-2026-8391, high).

Apart from this, the DOM: Bindings (WebIDL) component contains a use-after-free vulnerability (CVE-2026-8947, high), and a sandbox escape is possible in the Profile Backup component (CVE-2026-8401, high).

Update Instructions

  • OS 12: Upgrade the Firefox ESR app to version 140.11.

  • OS 11: IGEL is working on a version with updated Firefox ESR.

References