Description
A malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Thunderbird | — | 140.9 |
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 | 1:140.9.0esr-1 | — |
| Debian 13 | thunderbird | 1:140.9.0esr-1~deb13u1 | DSA-6179-1 |
| Debian 12 | thunderbird | 1:140.9.0esr-1~deb12u1 | DSA-6179-1 |
| Debian 11 | thunderbird | 1:140.9.0esr-1~deb11u1 | DLA-4511-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | mozjs102 +1 | No fix yet | — |
| Ubuntu 22.04 LTS | mozjs78 +3 | No fix yet | — |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | thunderbird | 140.9.0-1.el10_1 | RHSA-2026:6342 |
| RHEL 9 | thunderbird | 140.9.0-1.el9_7 | RHSA-2026:6188 |
| RHEL 8 | thunderbird | 140.9.0-1.el8_10 | RHSA-2026:6917 |
Show 13 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10.0 EUS | thunderbird | 140.9.0-1.el10_0 | RHSA-2026:8315 |
| RHEL 9.6 EUS | thunderbird | 140.9.0-1.el9_6 | RHSA-2026:8284 |
| RHEL 9.4 EUS | thunderbird | 140.9.0-1.el9_4 | RHSA-2026:8290 |
| RHEL 9.2 E4S | thunderbird | 140.9.0-1.el9_2 | RHSA-2026:8287 |
| RHEL 9.0 E4S | thunderbird | 140.9.0-1.el9_0 | RHSA-2026:8286 |
| RHEL 8.8 TUS | thunderbird | 140.9.0-1.el8_8 | RHSA-2026:8288 |
| RHEL 8.8 E4S | thunderbird | 140.9.0-1.el8_8 | RHSA-2026:8288 |
| RHEL 8.6 TUS | thunderbird | 140.9.0-1.el8_6 | RHSA-2026:8289 |
| RHEL 8.6 E4S | thunderbird | 140.9.0-1.el8_6 | RHSA-2026:8289 |
| RHEL 8.6 AUS | thunderbird | 140.9.0-1.el8_6 | RHSA-2026:8289 |
| RHEL 8.4 EUS Long Life | thunderbird | 140.9.0-1.el8_4 | RHSA-2026:8850 |
| RHEL 8.4 AUS | thunderbird | 140.9.0-1.el8_4 | RHSA-2026:8850 |
| RHEL 8.2 AUS | thunderbird | 140.9.0-1.el8_2 | RHSA-2026:8285 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | thunderbird | 140.9.0-1.el10_1.alma.1 | ALSA-2026:6342 |
| AlmaLinux 9 | thunderbird | 140.9.0-1.el9_7.alma.1 | ALSA-2026:6188 |
| AlmaLinux 8 | thunderbird | 140.9.0-1.el8_10.alma.1 | ALSA-2026:6917 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | thunderbird | 140.9.0-1.el10_1 | RLSA-2026:6342 |
| Rocky Linux 9 | thunderbird | 140.9.0-1.el9_7 | RLSA-2026:6188 |
| Rocky Linux 8 | thunderbird | 140.9.0-1.el8_10 | RLSA-2026:6917 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaThunderbird | 140.9.0-1.1 | openSUSE-SU-2026:10447-1 |
| openSUSE Leap 15.6 | MozillaThunderbird | 140.9.0-150200.8.263.1 | SUSE-SU-2026:1163-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | thunderbird | 140.9.0-1.amzn2.0.2 | ALAS2-2026-3241 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | thunderbird | 140.9.0-1.0.1.el10_1 | ELSA-2026-6342 |
| Oracle Linux 9 | thunderbird | 140.9.0-1.0.1.el9_7 | ELSA-2026-6188 |
| Oracle Linux 8 | thunderbird | 140.9.0-1.0.1.el8_10 | ELSA-2026-6917 |
Advisories 27
- WID-SEC-2026-0850 Mozilla Firefox und Mozilla Thunderbird: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 8, 2026
- ALSA-2026:6342 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:6188 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:6917 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:8850 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:8315 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:8290 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:8288 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:8289 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:8286 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:8287 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:8284 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:8285 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:6917 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:6342 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2026:6188 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- ALAS2-2026-3241 Important: thunderbird security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Apr 13, 2026
- RLSA-2026:6917 Important: thunderbird security update Rocky Linux Security Advisories · Apr 12, 2026
- RLSA-2026:6342 Important: thunderbird security update Rocky Linux Security Advisories · Apr 9, 2026
- RLSA-2026:6188 Important: thunderbird security update Rocky Linux Security Advisories · Apr 7, 2026
- ELSA-2026-6917 Important: thunderbird security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Apr 7, 2026
- SUSE-SU-2026:1163-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Apr 2, 2026
- ELSA-2026-6342 Important: thunderbird security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Apr 1, 2026
- ELSA-2026-6188 Important: thunderbird security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Mar 30, 2026
- openSUSE-SU-2026:10447-1 MozillaThunderbird-140.9.0-1.1 on GA media SUSE / openSUSE Security Updates · Mar 29, 2026
- DLA-4511-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 27, 2026
- DSA-6179-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 26, 2026