Improper Input Validation Affecting thunderbird package, versions [,153.2)[154,155)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published13 Oct 2026
- disclosed13 Oct 2026
- creditUnknown
Introduced: 13 Oct 2026
NewCVE-2026-84642 (opens in a new tab)How to fix?
Upgrade thunderbird to version 153.2, 155 or higher.
Overview
Affected versions of this package are vulnerable to Improper Input Validation due to improper handling of the mail.allowed_attachment_hostnames configuration, which is interpreted as a regular expression without proper escaping. An attacker can cause unintended hostnames to match and serve remote attachments by crafting specific hostnames that exploit the unescaped regular expression.