CVE-2025-3522

MEDIUM
2025-04-15 [email protected]
6.3
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

Lifecycle Timeline

3
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 6.3

Tags

Microsoft Open Redirect Google Mozilla Thunderbird Chrome Windows Redhat Suse

Description

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. This vulnerability affects Thunderbird < 137.0.2 and Thunderbird < 128.9.2.

Analysis

Thunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. Rated medium severity (CVSS 6.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Technical Context

This vulnerability is classified as Open Redirect (CWE-601), which allows attackers to redirect users to malicious websites via URL manipulation. 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. 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. Validate redirect destinations against an allowlist, avoid using user input in redirect URLs.

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: +0.2
CVSS: +32
POC: 0

Vendor Status

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CVE-2025-3522 vulnerability details – vuln.today
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