Unrated severityNVD Advisory· Published Sep 1, 2026

CVE-2026-84642

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.

Affected products

Mozilla Corporation/Thunderbirdllm-fuzzy
Range: before 155 and before 153.2

Patches

Vulnerability mechanics

References

bugzilla.mozilla.org/show_bug.cginvd
www.mozilla.org/security/advisories/mfsa2026-86/nvd
www.mozilla.org/security/advisories/mfsa2026-88/nvd

News mentions

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