Home/CVE/When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only t
CVE

CVE-2025-3523

When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only t

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.

MEDIUM · CVSS 6.4 EPSS 0.00106
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-451User Interface (UI) Misrepresentation of Critical Information
▤

Affected Products & Versions

2
mozilla thunderbird< 128.9.2
mozilla thunderbird>= 129.0 and < 137.0.2
▣

Scoring & Timeline

6.4
MEDIUM · CVSS v3.1 · security@mozilla.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD15 Apr 2025 · 03:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

14
usnUSN-7663-1
rhsaRHSA-2025:7507Important
suse-csafSUSE-SU-2025:1366-1
suse-csafopenSUSE-SU-2025:15000-1
rhsaRHSA-2025:4389Low
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
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
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