CVE-2026-84642: Vulnerability in Mozilla Thunderbird
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 and Thunderbird 153.2.
CVE-2026-84642: Vulnerability in Mozilla Thunderbird
Description
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 and Thunderbird 153.2.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-09-01T21:33:07.702Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-86/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-88/","vendor":"Mozilla"}]
Threat ID: 6a97492dacd9273b493ed28e
Added to database: 09/01/2026, 21:52:45 UTC
Last updated: 09/01/2026, 23:37:24 UTC
Views: 8
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