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CVE-2025-3523

6.4 · MEDIUM

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.

Published Apr 15, 2025CWE-451EPSS 0.32%

Overview

CVE-2025-3523 is a medium-severity vulnerability. It was published on April 15, 2025 and has a CVSS 3.1 base score of 6.4 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.4, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refbugzilla.mozilla.org/show_bug.cgi?id=1958385Refwww.mozilla.org/security/advisories/mfsa2025-26/Refwww.mozilla.org/security/advisories/mfsa2025-27/

How CyberStrike helps

Frequently asked questions

What is CVE-2025-3523?

CVE-2025-3523 is a medium-severity vulnerability. It was published on April 15, 2025 and has a CVSS 3.1 base score of 6.4 (MEDIUM).

How severe is CVE-2025-3523?

This vulnerability has a CVSS 3.1 base score of 6.4, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2025-3523?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-3523?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-3523 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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