Bug 2479861 (CVE-2026-8959) - CVE-2026-8959 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component
Summary: CVE-2026-8959 firefox: thunderbird: Sandbox escape due to incorrect boundary ...
Keywords:
Status: NEW
Alias: CVE-2026-8959
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-05-19 14:02 UTC by OSIDB Bzimport
Modified: 2026-05-27 18:33 UTC (History)
7 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

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System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:21381 0 None None None 2026-05-27 16:07:21 UTC

Description OSIDB Bzimport 2026-05-19 14:02:53 UTC 
Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 151 and Firefox ESR 140.11.
Comment 4 errata-xmlrpc 2026-05-27 16:07:20 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:21381 https://access.redhat.com/errata/RHSA-2026:21381
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