CVE-2025-3522

MEDIUM EPSS 13.3%
Published Apr 15, 20251y ago · Modified Jun 17, 20261w ago
6.3 CVSS 3.1
Medium
Find Similar
Published Apr 15, 2025 1y ago
Last Modified Jun 17, 2026 1w ago

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 was fixed in Thunderbird 137.0.2 and Thunderbird 128.9.2.

CVSS Details

Base Score
6.3
Exploitability
2.8
Impact
3.4
Vector string
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

Threat Intelligence

EPSS Exploit Probability
13.3% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-601

Affected Products 2

VendorProductVersionRange
mozillathunderbird* <128.9.2
mozillathunderbird*≥129.0  –  <137.0.2

References 3

  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1955372
    Permissions Required
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2025-26/
    Vendor Advisory
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2025-27/
    Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.