CVE-2025-3909
Publication date 14 May 2025
Last updated 22 July 2025
Ubuntu priority
Cvss 3 Severity Score
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 affects Thunderbird < 128.10.1 and Thunderbird < 138.0.1.
Status
Package | Ubuntu Release | Status |
---|---|---|
thunderbird | 25.04 plucky |
Not affected
|
24.04 LTS noble |
Not affected
|
|
22.04 LTS jammy |
Fixed 1:128.12.0+build1-0ubuntu0.22.04.1
|
|
20.04 LTS focal | Not in release |
Severity score breakdown
Parameter | Value |
---|---|
Base score |
|
Attack vector | Network |
Attack complexity | Low |
Privileges required | None |
User interaction | None |
Scope | Unchanged |
Confidentiality | Low |
Integrity impact | Low |
Availability impact | None |
Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N |
References
Related Ubuntu Security Notices (USN)
- USN-7663-1
- Thunderbird vulnerabilities
- 22 July 2025