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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Thunderbird | — | 128.10.1 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | thunderbird | 1:128.10.1esr-1 | — |
| Debian 13 | thunderbird | 1:128.10.1esr-1 | — |
| Debian 12 | thunderbird | 1:128.10.1esr-1~deb12u1 | DSA-5921-1 |
| Debian 11 | thunderbird | 1:128.10.1esr-1~deb11u1 | DLA-4167-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | thunderbird | 1:128.12.0+build1-0ubuntu0.22.04.1 | USN-7663-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | thunderbird | 128.10.1-1.el10_0 | RHSA-2025:8196 |
| RHEL 9 | thunderbird | 128.10.1-1.el9_6 | RHSA-2025:8203 |
| RHEL 8 | thunderbird | 128.11.0-1.el8_10 | RHSA-2025:8756 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9.4 EUS | thunderbird | 128.10.1-1.el9_4 | RHSA-2025:8325 |
| RHEL 9.2 EUS | thunderbird | 128.10.1-1.el9_2 | RHSA-2025:8326 |
| RHEL 9.0 E4S | thunderbird | 128.10.1-1.el9_0 | RHSA-2025:8324 |
| RHEL 8.8 TUS | thunderbird | 128.10.1-1.el8_8 | RHSA-2025:8784 |
| RHEL 8.8 E4S | thunderbird | 128.10.1-1.el8_8 | RHSA-2025:8784 |
| RHEL 8.6 TUS | thunderbird | 128.10.1-1.el8_6 | RHSA-2025:8594 |
| RHEL 8.6 E4S | thunderbird | 128.10.1-1.el8_6 | RHSA-2025:8594 |
| RHEL 8.6 AUS | thunderbird | 128.10.1-1.el8_6 | RHSA-2025:8594 |
| RHEL 8.4 AUS | thunderbird | 128.10.1-1.el8_4 | RHSA-2025:8507 |
| RHEL 8.2 AUS | thunderbird | 128.10.1-1.el8_2 | RHSA-2025:8391 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | thunderbird | 128.10.1-1.el10_0.alma.1 | ALSA-2025:8196 |
| AlmaLinux 8 | thunderbird | 128.11.0-1.el8_10.alma.1 | ALSA-2025:8756 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | thunderbird | 128.10.1-1.el10_0 | RLSA-2025:8196 |
| Rocky Linux 9 | thunderbird | 128.10.1-1.el9_6 | RLSA-2025:8203 |
| Rocky Linux 8 | thunderbird | 128.11.0-1.el8_10 | RLSA-2025:8756 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | MozillaThunderbird | 128.10.1-150200.8.215.1 | SUSE-SU-2025:01660-2 |
| SLES 15 SP6 | MozillaThunderbird | 128.10.1-150200.8.215.1 | SUSE-SU-2025:01660-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaThunderbird | 128.10.1-1.1 | openSUSE-SU-2025:15131-1 |
| openSUSE Leap 15.6 | MozillaThunderbird | 128.10.1-150200.8.215.1 | SUSE-SU-2025:01660-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | thunderbird | 128.10.1-1.amzn2.0.1 | ALAS2-2025-2859 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | thunderbird | 128.11.0-1.0.1.el10_0 | ELSA-2025-8196 |
| Oracle Linux 9 | thunderbird | 128.10.1-1.0.1.el9_6 | ELSA-2025-8203 |
| Oracle Linux 8 | thunderbird | 128.11.0-1.0.1.el8_10 | ELSA-2025-8756 |
Advisories 27
- ALSA-2025:8196 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:8756 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2025:8784 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8594 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8756 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8325 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8326 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8203 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8324 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8196 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8507 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- RHSA-2025:8391 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Aug 7, 2026
- USN-7663-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- SUSE-SU-2025:01660-2 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Mar 23, 2026
- DSA-5921-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-4167-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2025:15131-1 MozillaThunderbird-128.10.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 5, 2026
- SUSE-SU-2025:01660-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-1850 Xerox FreeFlow Print Server: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff BSI CERT-Bund (WID) · Nov 17, 2025
- RLSA-2025:8196 Important: thunderbird security update Rocky Linux Security Advisories · Oct 8, 2025
- RLSA-2025:8203 Important: thunderbird security update Rocky Linux Security Advisories · Oct 4, 2025
- RLSA-2025:8756 Important: thunderbird security update Rocky Linux Security Advisories · Jul 29, 2025
- WID-SEC-2025-1062 Mozilla Thunderbird: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jun 30, 2025
- ELSA-2025-8196 Important: thunderbird security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Jun 30, 2025
- ALAS2-2025-2859 Important: thunderbird security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Jun 24, 2025
- ELSA-2025-8756 Important: thunderbird security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Jun 10, 2025
- ELSA-2025-8203 Important: thunderbird security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · May 27, 2025