CVEvulnerability

CVE-2025-3909

8.1 HIGH Published 2025-05-14 Modified 2026-06-17 Official page ↗
Status
Modified
Published
2025-05-14
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 (134c704f-9b21-4f2e-91b3-4a467353bcc0)
8.1 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Weaknesses
CWE-356

Description

Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.

Affected configurations

• mozilla thunderbird (< 128.10.1) • mozilla thunderbird (>= 129.0 < 138.0.1)

Related

Weakness · CWE (1)

  • CWE-356 Missing User Interaction for Potentially Unsafe Action weakness

References