How to fix CVE-2025-3523?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Monitor vendor channels for patch availability.

Is Thunderbird affected by CVE-2025-3523?

Organizations using When an email should be aware of moderate risk from CVE-2025-3523 rated CVSS 6.4. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.

CVE-2025-3523

MEDIUM

2025-04-15 [email protected]

6.4

CVSS 3.1

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

High

Availability

Low

Lifecycle Timeline

Patch Released

Apr 06, 2026 - 02:30 nvd

Patch available

Analysis Generated

Mar 28, 2026 - 18:36 vuln.today

CVE Published

Apr 15, 2025 - 15:16 nvd

MEDIUM 6.4

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.

Analysis

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. Rated medium severity (CVSS 6.4), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.

Technical Context

This vulnerability is classified under CWE-451. 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. Affected products include: Mozilla Thunderbird.

Affected Products

Mozilla Thunderbird.

Remediation

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +0.2

CVSS: +32

POC: 0

Vendor Status

CVE-2025-3523 vulnerability details – vuln.today

Back

CVE-2025-3523

CVSS Vector

Lifecycle Timeline

Tags

Description

Analysis

Technical Context

Affected Products

Remediation

Priority Score

Vendor Status

Share

CVE-2025-3523

CVSS Vector

Lifecycle Timeline

Tags

Description

Analysis

Technical Context

Affected Products

Remediation

Priority Score

Vendor Status

Share

External POC / Exploit Code