CVE-2025-3522
First published: Tue Apr 15 2025(Updated: )
Thunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. When an email is opened, Thunderbird accesses the specified URL to determine file size, and navigates to it when the user clicks the attachment. Because the URL is not validated or sanitized, it can reference internal resources like chrome:// or SMB share file:// links, potentially leading to hashed Windows credential leakage and opening the door to more serious security issues.
Credit: security@mozilla.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Thunderbird | <137.0.2 | |
| Thunderbird | <128.9.2 | |
| Thunderbird | <137.0.2 | 137.0.2 |
| Thunderbird | <128.9.2 | 128.9.2 |
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Reference Links
Peer vulnerabilities
(Found alongside the following vulnerabilities)
Frequently Asked Questions
What is the severity of CVE-2025-3522?
CVE-2025-3522 is considered a moderate severity vulnerability due to its potential for exploitation through unvalidated URL handling.
How do I fix CVE-2025-3522?
To fix CVE-2025-3522, update Thunderbird to the latest version beyond 137.0.2.
What versions of Thunderbird are affected by CVE-2025-3522?
CVE-2025-3522 affects Thunderbird versions up to and including 137.0.2 and 128.9.2.
What causes the vulnerability in CVE-2025-3522?
The vulnerability in CVE-2025-3522 is caused by Thunderbird processing the X-Mozilla-External-Attachment-URL header without proper URL validation.
Is user interaction required to exploit CVE-2025-3522?
Yes, user interaction is required to exploit CVE-2025-3522 as the vulnerability is triggered when the user opens an affected email.
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