Bug 2527114 (CVE-2026-84642) - CVE-2026-84642 thunderbird: Allowed UNC hostnames for attachments interpreted as a regular expression
Summary: CVE-2026-84642 thunderbird: Allowed UNC hostnames for attachments interpreted...
Keywords:
Status: NEW
Alias: CVE-2026-84642
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-01 21:41 UTC by OSIDB Bzimport
Modified: 2026-09-21 16:49 UTC (History)
5 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Attachments (Terms of Use)

Description OSIDB Bzimport 2026-09-01 21:41:59 UTC 
The values of the mail.allowed_attachment_hostnames advanced config setting were used in a regular expression without escaping. For some possible valid hostnames, this could allow certain unintended hostnames to also match and serve remote attachments. This vulnerability was fixed in Thunderbird 155.
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