CVE-2025-3909 (GCVE-0-2025-3909)

Vulnerability from cvelistv5 – Published: 2025-05-14 16:56 – Updated: 2026-04-13 14:27
VLAI
Title
JavaScript Execution via Spoofed PDF Attachment and file:/// Link
Summary
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.
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-05-16 03:55 UTC
CWE
  • CWE-356 - Product UI does not Warn User of Unsafe Actions
Assigner
mozilla CNA under the mitre root
CNA scorecard E 38/100 over 683 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Mozilla Thunderbird Unaffected: 128.10.1 , ≤ 128.* (rpm)
Unaffected: 138.0.1 , ≤ * (rpm)
guessed Create a notification for this product.
Credits
Dario Weißer
Show details on NVD website
To clipboard 

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