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When an email contains multiple attachments with external...

Moderate severity Unreviewed Published Apr 15, 2025 to the GitHub Advisory Database • Updated Apr 15, 2025

Package

No package listed— Suggest a package

Affected versions

Unknown

Patched versions

Unknown

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 affects Thunderbird < 137.0.2 and Thunderbird < 128.9.2.

References

Published by the National Vulnerability Database Apr 15, 2025
Published to the GitHub Advisory Database Apr 15, 2025
Last updated Apr 15, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(20th percentile)

Weaknesses

User Interface (UI) Misrepresentation of Critical Information

The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks. Learn more on MITRE.

CVE ID

CVE-2025-3523

GHSA ID

GHSA-4h7q-pj8m-5675

Source code

No known source code

Dependabot alerts are not supported on this advisory because it does not have a package from a supported ecosystem with an affected and fixed version.

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