CVE-2025-3522
Last modified
CVE-2025-3522 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. Thunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. When an email is opened, Thunderbird accesses the specified URL to determine file size, and navigates to it when the user clicks the attachment. EPSS estimates a 0.23% chance of exploitation in the next 30 days.
Description
Thunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. When an email is opened, Thunderbird accesses the specified URL to determine file size, and navigates to it when the user clicks the attachment. Because the URL is not validated or sanitized, it can reference internal resources like chrome:// or SMB share file:// links, potentially leading to hashed Windows credential leakage and opening the door to more serious security issues. This vulnerability was fixed in Thunderbird 137.0.2 and Thunderbird 128.9.2.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | < 128.9.2 |
| Mozilla | Thunderbird | >= 129.0, < 137.0.2 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1955372Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2025-26/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-27/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
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