Email Client Vulnerability in Thunderbird by Mozilla
CVE-2025-3932

6.5MEDIUM

Key Information:

Vendor

Mozilla
Status
Thunderbird
Vendor
CVE Published:
14 May 2025

What is CVE-2025-3932?

A vulnerability in Thunderbird allowed attackers to craft emails featuring tracking links masked as attachments. When users attempted to open these attachments, Thunderbird would automatically access the linked content, bypassing configurations intended to block remote content. Mozilla has released patches to prevent access to web pages specified in the X-Mozilla-External-Attachment-URL header, ensuring that users are protected from this exploit in affected versions.

Affected Version(s)

Thunderbird < 128.10.1

Thunderbird < 138.0.1

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1960412
https://www.mozilla.org/security/advisories/mfsa2025-34/
https://www.mozilla.org/security/advisories/mfsa2025-35/

CVSS V3.1

Score:
6.5
Severity:
MEDIUM
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Dario WeiĂźer
.
CVE-2025-3932 : Email Client Vulnerability in Thunderbird by Mozilla