Thunderbirds 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.
This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | RedHat | thunderbird-0:128.10.1-1.el10_0 | * |
| Red Hat Enterprise Linux 8.2 Advanced Update Support | RedHat | thunderbird-0:128.10.1-1.el8_2 | * |
| Red Hat Enterprise Linux 9 | RedHat | thunderbird-0:128.10.1-1.el9_6 | * |
| Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions | RedHat | thunderbird-0:128.10.1-1.el9_0 | * |
| Red Hat Enterprise Linux 9.2 Extended Update Support | RedHat | thunderbird-0:128.10.1-1.el9_2 | * |
| Red Hat Enterprise Linux 9.4 Extended Update Support | RedHat | thunderbird-0:128.10.1-1.el9_4 | * |
| Thunderbird | Ubuntu | focal | * |