Description
Thunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. When an email is opened, Thunderbird accesses the specified URL to determine file size, and navigates to it when the user clicks the attachment. Because the URL is not validated or sanitized, it can reference internal resources like chrome:// or SMB share file:// links, potentially leading to hashed Windows credential leakage and opening the door to more serious security issues. This vulnerability was fixed in Thunderbird 137.0.2 and Thunderbird 128.9.2.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Thunderbird | — | 128.9.2 |
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 | 1:128.10.0esr-1 | — |
| Debian 13 | thunderbird | 1:128.10.0esr-1 | — |
| Debian 12 | thunderbird | 1:128.10.0esr-1~deb12u1 | DSA-5912-1 |
| 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 | 128.10.0-1.el10_0 | RHSA-2025:7507 |
| RHEL 9 | thunderbird | 128.9.2-1.el9_5 | RHSA-2025:7435, RHSA-2025:4229 |
| RHEL 8 | thunderbird | 128.9.2-1.el8_10 | RHSA-2025:4649 |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9.4 EUS | thunderbird | 128.9.2-1.el9_4 | RHSA-2025:4512 |
| RHEL 9.2 EUS | thunderbird | 128.9.2-1.el9_2 | RHSA-2025:4513 |
| RHEL 9.0 E4S | thunderbird | 128.9.2-1.el9_0 | RHSA-2025:4514 |
| RHEL 8.8 EUS | thunderbird | 128.9.2-1.el8_8 | RHSA-2025:4617 |
| RHEL 8.6 TUS | thunderbird | 128.9.2-1.el8_6 | RHSA-2025:4665 |
| RHEL 8.6 E4S | thunderbird | 128.9.2-1.el8_6 | RHSA-2025:4665 |
| RHEL 8.6 AUS | thunderbird | 128.9.2-1.el8_6 | RHSA-2025:4665 |
| RHEL 8.4 TUS | thunderbird | 128.9.2-1.el8_4 | RHSA-2025:4654 |
| RHEL 8.4 E4S | thunderbird | 128.9.2-1.el8_4 | RHSA-2025:4654 |
| RHEL 8.4 AUS | thunderbird | 128.9.2-1.el8_4 | RHSA-2025:4654 |
| RHEL 8.2 AUS | thunderbird | 128.9.2-1.el8_2 | RHSA-2025:4389 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | thunderbird | 128.10.0-1.el10_0.alma.1 | ALSA-2025:7507 |
| AlmaLinux 9 | thunderbird | 128.9.2-1.el9_5.alma.1 | ALSA-2025:7435, ALSA-2025:4229 |
| AlmaLinux 8 | thunderbird | 128.9.2-1.el8_10.alma.1 | ALSA-2025:4649 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 9 | thunderbird | 128.10.0-1.el9_5 | RLSA-2025:7435 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP6 | MozillaThunderbird | 128.9.2-150200.8.209.1 | SUSE-SU-2025:1366-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaThunderbird | 128.9.2-1.1 | openSUSE-SU-2025:15000-1 |
| openSUSE Leap 15.6 | MozillaThunderbird | 128.9.2-150200.8.209.1 | SUSE-SU-2025:1366-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | thunderbird | 128.10.0-1.amzn2.0.1 | ALAS2-2025-2858 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | thunderbird | 128.11.0-1.0.1.el10_0 | ELSA-2025-7507 |
| Oracle Linux 9 | thunderbird | 128.9.2-1.0.1.el9_5 | ELSA-2025-7435, ELSA-2025-4229 |
| Oracle Linux 8 | thunderbird | 128.9.2-1.0.1.el8_10 | ELSA-2025-4649 |
Advisories 27
- ALSA-2025:7507 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:7435 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:4229 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:4649 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2025:4649 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2025:7507 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:7435 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:4665 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:4654 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:4617 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:4514 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:4512 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:4513 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:4389 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2025:4229 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- USN-7663-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-5912-1 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-2025:15000-1 MozillaThunderbird-128.9.2-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2025:1366-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- ALAS2-2025-2858 Important: thunderbird security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 29, 2025
- RLSA-2025:7435 Important: thunderbird security update Rocky Linux Security Advisories · Jul 29, 2025
- WID-SEC-2025-0803 Mozilla Thunderbird und Thunderbird ESR: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jun 30, 2025
- ELSA-2025-7507 Important: thunderbird security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Jun 30, 2025
- ELSA-2025-7435 Important: thunderbird security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · May 22, 2025
- ELSA-2025-4649 Important: thunderbird security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · May 7, 2025
- ELSA-2025-4229 Important: thunderbird security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Apr 28, 2025