Description
A crafted HTML email using mailbox:/// links can trigger automatic, unsolicited downloads of .pdf files to the user's desktop or home directory without prompting, even if auto-saving is disabled. This behavior can be abused to fill the disk with garbage data (e.g. using /dev/urandom on Linux) or to leak Windows credentials via SMB links when the email is viewed in HTML mode. While user interaction is required to download the .pdf file, visual obfuscation can conceal the download trigger. Viewing the email in HTML mode is enough to load external content. This vulnerability was fixed in Thunderbird 128.11.1 and Thunderbird 139.0.2.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Thunderbird | — | 128.11.1 |
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 | 1:128.12.0esr-1 | — |
| Debian 13 | thunderbird | 1:128.12.0esr-1 | — |
| Debian 12 | thunderbird | 1:128.12.0esr-1~deb12u1 | DSA-5959-1 |
| Debian 11 | thunderbird | 1:128.12.0esr-1~deb11u1 | DLA-4239-1 |
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 | 128.12.0-1.el10_0 | RHSA-2025:10195 |
| RHEL 9 | thunderbird | 128.12.0-1.el9_6 | RHSA-2025:10196 |
| RHEL 8 | thunderbird | 128.12.0-1.el8_10 | RHSA-2025:10246 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9.4 EUS | thunderbird | 128.12.0-1.el9_4 | RHSA-2025:10159 |
| RHEL 9.2 E4S | thunderbird | 128.12.0-1.el9_2 | RHSA-2025:10160 |
| RHEL 9.0 E4S | thunderbird | 128.12.0-1.el9_0 | RHSA-2025:10161 |
| RHEL 8.8 TUS | thunderbird | 128.12.0-1.el8_8 | RHSA-2025:10163 |
| RHEL 8.8 E4S | thunderbird | 128.12.0-1.el8_8 | RHSA-2025:10163 |
| RHEL 8.6 TUS | thunderbird | 128.12.0-1.el8_6 | RHSA-2025:10164 |
| RHEL 8.6 E4S | thunderbird | 128.12.0-1.el8_6 | RHSA-2025:10164 |
| RHEL 8.6 AUS | thunderbird | 128.12.0-1.el8_6 | RHSA-2025:10164 |
| RHEL 8.4 AUS | thunderbird | 128.12.0-1.el8_4 | RHSA-2025:10165 |
| RHEL 8.2 AUS | thunderbird | 128.12.0-1.el8_2 | RHSA-2025:10166 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | thunderbird | 128.12.0-1.el10_0.alma.1 | ALSA-2025:10195 |
| AlmaLinux 9 | thunderbird | 128.12.0-1.el9_6.alma.1 | ALSA-2025:10196 |
| AlmaLinux 8 | thunderbird | 128.12.0-1.el8_10.alma.1 | ALSA-2025:10246 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | thunderbird | 128.12.0-1.el10_0 | RLSA-2025:10195 |
| Rocky Linux 9 | thunderbird | 128.12.0-1.el9_6 | RLSA-2025:10196 |
| Rocky Linux 8 | thunderbird | 128.12.0-1.el8_10 | RLSA-2025:10246 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | MozillaThunderbird | 128.11.1-150200.8.224.1 | SUSE-SU-2025:02158-1 |
| SLES 15 SP6 | MozillaThunderbird | 128.11.1-150200.8.224.1 | SUSE-SU-2025:02158-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaThunderbird | 128.11.1-2.1 | openSUSE-SU-2025:15204-1 |
| openSUSE Leap 15.6 | MozillaThunderbird | 128.11.1-150200.8.224.1 | SUSE-SU-2025:02158-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | thunderbird | 128.11.1-1.amzn2.0.1 | ALAS2-2025-2896 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | thunderbird | 128.12.0-1.0.1.el10_0 | ELSA-2025-10195 |
| Oracle Linux 9 | thunderbird | 128.12.0-1.0.1.el9_6 | ELSA-2025-10196 |
| Oracle Linux 8 | thunderbird | 128.12.0-1.0.1.el8_10 | ELSA-2025-10246 |
Advisories 26
- ALSA-2025:10195 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:10196 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:10246 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2025:10246 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10196 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10195 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10165 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10166 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10163 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10164 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10160 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10161 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- RHSA-2025:10159 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 30, 2026
- USN-7663-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- openSUSE-SU-2025:15204-1 MozillaThunderbird-128.11.1-2.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- DLA-4239-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-5959-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2025:02158-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- RLSA-2025:10196 Important: thunderbird security update Rocky Linux Security Advisories · Oct 7, 2025
- RLSA-2025:10195 Important: thunderbird security update Rocky Linux Security Advisories · Oct 3, 2025
- RLSA-2025:10246 Important: thunderbird security update Rocky Linux Security Advisories · Jul 29, 2025
- WID-SEC-2025-1301 Mozilla Thunderbird: Schwachstelle ermöglicht Denial of Service und Offenlegung von Informationen BSI CERT-Bund (WID) · Jul 22, 2025
- ELSA-2025-10195 Important: thunderbird security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Jul 2, 2025
- ELSA-2025-10196 Important: thunderbird security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Jul 2, 2025
- ELSA-2025-10246 Important: thunderbird security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Jul 2, 2025
- ALAS2-2025-2896 Important: thunderbird security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Jun 24, 2025