CVE-2025-3932 Tracking Links in Attachments Bypassed Remote Content Blocking
Attackers can bypass remote content blocking in Thunderbird by crafting emails with tracking links disguised as attachments, automatically triggering web requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-3932?
CVE-2025-3932 is a medium-severity vulnerability in Mozilla Thunderbird, published on 14 May 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-288
Which versions are affected by CVE-2025-3932?
It affects 1 product.
Products include Mozilla Thunderbird.
How do I fix CVE-2025-3932?
Upgrade to a fixed version.
Is CVE-2025-3932 being exploited?
There is no known exploitation of CVE-2025-3932 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Thunderbird
Sources
Also known as DEBIAN-CVE-2025-3932, GHSA-jfxg-6gv4-f2gh, UBUNTU-CVE-2025-3932.