CVE-2025-3932: thunderbird — Fix

Description

It was possible to craft an email that showed a tracking link as an attachment. If the user attempted to open the attachment, Thunderbird automatically accessed the link. The configuration to block remote content did not prevent that. Thunderbird has been fixed to no longer allow access to web pages listed in the X-Mozilla-External-Attachment-URL header of an email. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.

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CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Weakness Type (CWE)

CWE-288 CWE-288

Affected Products

Vendor	Product	Versions
mozilla	thunderbird	< 128.10.1
mozilla	thunderbird	129.0 — 138.0.1

References

Advisories & Patches

https://www.mozilla.org/security/advisories/mfsa2025-34/ https://www.mozilla.org/security/advisories/mfsa2025-35/

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=1960412 https://lists.debian.org/debian-lts-announce/2025/05/msg00022.html

Frequently Asked Questions

What is CVE-2025-3932? +

It was possible to craft an email that showed a tracking link as an attachment. If the user attempted to open the attachment, Thunderbird automatically accessed the link. The configuration to block remote content did not prevent that. Thunderbird has been fixed to no longer allow access to web pages listed in the X-Mozilla-External-Attachment-URL header of an email. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2025-3932? +

CVE-2025-3932 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-3932? +

CVE-2025-3932 affects products from mozilla, specifically: thunderbird. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-3932? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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