Description
Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox | — | 115.40 |
| Mozilla | Thunderbird | — | 140.15 |
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 | firefox-esr | 140.15.0esr-1 | — |
| Debian 14 | thunderbird | 1:153.2.0esr-1 | — |
| Debian 13 | firefox-esr | 140.15.0esr-1~deb13u1 | — |
| Debian 13 | thunderbird | 1:140.15.0esr-1~deb13u1 | — |
| Debian 12 | firefox-esr | 140.15.0esr-1~deb12u1 | — |
| Debian 12 | thunderbird | 1:140.15.0esr-1~deb12u1 | — |
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 | firefox | 140.15.0-1.el10_2 | RHSA-2026:67129 |
| RHEL 10 | thunderbird | 140.16.0-1.el10_2 | RHSA-2026:73130 |
| RHEL 9 | firefox +1 | 140.15.0-1.el9_8 | RHSA-2026:67133 |
| RHEL 9 | thunderbird | 140.16.0-1.el9_8 | RHSA-2026:70642 |
| RHEL 8 | firefox | 140.15.0-1.el8_10 | RHSA-2026:68549 |
| RHEL 8 | thunderbird | 140.16.0-1.el8_10 | RHSA-2026:73971 |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10.0 EUS | firefox +1 | 140.15.0-1.el10_0 | RHSA-2026:77631, RHSA-2026:77610 |
| RHEL 9.6 EUS | firefox +2 | 140.15.0-1.el9_6 | RHSA-2026:80503, RHSA-2026:76895 |
| RHEL 9.4 E4S | firefox +2 | 140.15.0-1.el9_4 | RHSA-2026:77627, RHSA-2026:76740 |
| RHEL 9.2 E4S | firefox +2 | 140.15.0-1.el9_2 | RHSA-2026:77632, RHSA-2026:76742 |
| RHEL 8.8 TUS | firefox | 140.15.0-1.el8_8 | RHSA-2026:76746 |
| RHEL 8.8 TUS | thunderbird | 140.16.0-1.el8_8 | RHSA-2026:81912 |
| RHEL 8.8 E4S | firefox | 140.15.0-1.el8_8 | RHSA-2026:76746 |
| RHEL 8.8 E4S | thunderbird | 140.16.0-1.el8_8 | RHSA-2026:81912 |
| RHEL 8.6 EUS Long Life | firefox | 140.15.0-1.el8_6 | RHSA-2026:76745 |
| RHEL 8.6 EUS Long Life | thunderbird | 140.16.0-1.el8_6 | RHSA-2026:81913 |
| RHEL 8.6 AUS | firefox | 140.15.0-1.el8_6 | RHSA-2026:76745 |
| RHEL 8.6 AUS | thunderbird | 140.16.0-1.el8_6 | RHSA-2026:81913 |
| RHEL 8.4 EUS Long Life | firefox | 140.15.0-1.el8_4 | RHSA-2026:76894 |
| RHEL 8.4 EUS Long Life | thunderbird | 140.16.0-1.el8_4 | RHSA-2026:82122 |
| RHEL 8.4 AUS | firefox | 140.15.0-1.el8_4 | RHSA-2026:76894 |
| RHEL 8.4 AUS | thunderbird | 140.16.0-1.el8_4 | RHSA-2026:82122 |
| RHEL 7 ELS | firefox | 140.15.0-1.el7_9 | RHSA-2026:76741 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | firefox | 140.15.0-1.el10_2 | ALSA-2026:67129 |
| AlmaLinux 10 | thunderbird | 140.16.0-1.el10_2.alma.1 | ALSA-2026:73130 |
| AlmaLinux 9 | firefox +1 | 140.15.0-1.el9_8.alma.1 | ALSA-2026:67133 |
| AlmaLinux 9 | thunderbird | 140.16.0-1.el9_8.alma.1 | ALSA-2026:70642 |
| AlmaLinux 8 | firefox | 140.15.0-1.el8_10.alma.1 | ALSA-2026:68549 |
| AlmaLinux 8 | thunderbird | 140.16.0-1.el8_10.alma.1 | ALSA-2026:73971 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | firefox | 140.15.0-1.el10_2 | RLSA-2026:67129 |
| Rocky Linux 10 | thunderbird | 140.16.0-1.el10_2 | RLSA-2026:73130 |
| Rocky Linux 9 | firefox | 140.15.0-1.el9_8 | RLSA-2026:67133 |
| Rocky Linux 9 | thunderbird | 140.16.0-1.el9_8 | RLSA-2026:70642 |
| Rocky Linux 8 | firefox | 140.15.0-1.el8_10 | RLSA-2026:68549 |
| Rocky Linux 8 | thunderbird | 140.16.0-1.el8_10 | RLSA-2026:73971 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP7 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP7 | MozillaThunderbird | 153.2.0-150400.13.3.1 | SUSE-SU-2026:4268-1 |
| SLES 15 SP7 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP7 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP6 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP6 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP6 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP6 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP5 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP5 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP5 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP5 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP4 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP4 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP4 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP4 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 12 SP5 | MozillaFirefox | 153.2.0-118.5.4 | SUSE-SU-2026:4140-1 |
| SLES 12 SP5 | MozillaFirefox-branding-SLE | 153-41.3.8 | SUSE-SU-2026:4140-1 |
| SLES 12 SP5 | mozilla-nspr | 4.39-19.39.1 | SUSE-SU-2026:4140-1 |
| SLES 12 SP5 | mozilla-nss | 3.125-58.147.1 | SUSE-SU-2026:4140-1 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | MozillaFirefox | 153.2.0-160000.1.1 | SUSE-SU-2026:23784-1 |
| SLES for SAP 15 SP6 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP6 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP6 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP6 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP5 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP5 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP5 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP5 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP4 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP4 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP4 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP4 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 16.0 | MozillaFirefox | 153.2.0-160000.1.1 | SUSE-SU-2026:23784-1 |
| SLE Micro 5.5 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.5 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.4 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.4 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.3 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.3 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP5 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP5 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP5 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP5 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP4 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP4 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP4 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP4 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 155.0-1.1 | openSUSE-SU-2026:11677-1 |
| openSUSE Tumbleweed | MozillaThunderbird | 140.15.0-1.1 | openSUSE-SU-2026:11678-1 |
| openSUSE Tumbleweed | firefox-esr | 153.2.0-1.1 | openSUSE-SU-2026:11666-1 |
| openSUSE Leap 16.0 | MozillaFirefox | 153.2.0-160000.1.1 | openSUSE-SU-2026:21853-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | firefox | 140.16.0-1.amzn2023.0.1 | ALAS2023-2026-3126 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | thunderbird | 140.16.0-1.0.1.el10_2 | ELSA-2026-73130 |
| Oracle Linux 9 | thunderbird | 140.16.0-1.0.1.el9_8 | ELSA-2026-70642 |
| Oracle Linux 8 | firefox | 140.15.0-1.0.1.el8_10 | ELSA-2026-68549 |
| Oracle Linux 8 | thunderbird | 140.16.0-1.0.1.el8_10 | ELSA-2026-73971 |
| Oracle Linux 7 | firefox | 140.15.0-1.0.1.el7_9 | ELSA-2026-76741 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | firefox +1 | 155.0.1-r0 | — |
Advisories 48
- WID-SEC-2026-3132 Mozilla Firefox und Thunderbird: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 8, 2026
- ELSA-2026-76741 Important: firefox security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Nov 6, 2026
- ALSA-2026:67133 Important: firefox security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:73130 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:67129 Important: firefox security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:70642 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:73971 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:68549 Important: firefox security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:82122 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- RHSA-2026:81912 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- RHSA-2026:81913 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- RHSA-2026:73971 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- RHSA-2026:73130 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- RHSA-2026:70642 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- RHSA-2026:80503 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:77632 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:77631 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:77610 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:77627 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:76894 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:76895 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:76745 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:76746 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:76742 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:76741 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:76740 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:68549 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:67133 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:67129 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RLSA-2026:73971 Important: thunderbird security update Rocky Linux Security Advisories · Oct 1, 2026
- ELSA-2026-73971 Important: thunderbird security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 1, 2026
- RLSA-2026:73130 Important: thunderbird security update Rocky Linux Security Advisories · Sep 30, 2026
- ELSA-2026-73130 Important: thunderbird security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Sep 29, 2026
- ALAS2023-2026-3126 Important: firefox security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- SUSE-SU-2026:4140-1 Security update for MozillaFirefox, mozilla-nspr, mozilla-nss, rust-cbindgen SUSE / openSUSE Security Updates · Sep 28, 2026
- SUSE-SU-2026:23784-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Sep 27, 2026
- RLSA-2026:67129 Important: firefox security update Rocky Linux Security Advisories · Sep 27, 2026
- RLSA-2026:67133 Important: firefox security update Rocky Linux Security Advisories · Sep 27, 2026
- RLSA-2026:68549 Important: firefox security update Rocky Linux Security Advisories · Sep 27, 2026
- RLSA-2026:70642 Important: thunderbird security update Rocky Linux Security Advisories · Sep 25, 2026
- ELSA-2026-70642 Important: thunderbird security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Sep 24, 2026
- SUSE-SU-2026:4268-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Sep 19, 2026
- openSUSE-SU-2026:21853-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Sep 17, 2026
- ELSA-2026-68549 Important: firefox security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Sep 17, 2026
- SUSE-SU-2026:4156-1 Security update for MozillaFirefox, MozillaFirefox-branding-SLE, mozilla-nspr, mozilla-nss, rust-cbindgen SUSE / openSUSE Security Updates · Sep 15, 2026
- openSUSE-SU-2026:11677-1 MozillaFirefox-155.0-1.1 on GA media SUSE / openSUSE Security Updates · Sep 5, 2026
- openSUSE-SU-2026:11678-1 MozillaThunderbird-140.15.0-1.1 on GA media SUSE / openSUSE Security Updates · Sep 5, 2026
- openSUSE-SU-2026:11666-1 firefox-esr-153.2.0-1.1 on GA media SUSE / openSUSE Security Updates · Sep 3, 2026
References
- High Severity internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
- Low Severity internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
- Moderate Severity internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
- https://www.mozilla.org/security/advisories/mfsa2026-82/
- https://www.mozilla.org/security/advisories/mfsa2026-83/
- https://www.mozilla.org/security/advisories/mfsa2026-84/
- https://www.mozilla.org/security/advisories/mfsa2026-85/
- https://www.mozilla.org/security/advisories/mfsa2026-86/
- https://www.mozilla.org/security/advisories/mfsa2026-87/
- https://www.mozilla.org/security/advisories/mfsa2026-88/