CVE-2025-3523
Last modified
CVE-2025-3523 is a medium-severity vulnerability rated 6.4/10 on the CVSS scale. When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only the last link is shown when hovering over any attachment. Although the correct link is used on click, the misleading hover text could trick users into downloading content from untrusted sources. EPSS estimates a 0.26% chance of exploitation in the next 30 days.
Description
When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only the last link is shown when hovering over any attachment. Although the correct link is used on click, the misleading hover text could trick users into downloading content from untrusted sources. This vulnerability was fixed in Thunderbird 137.0.2 and Thunderbird 128.9.2.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/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=1958385Permissions 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
Frequently Asked Questions
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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